WO2025031957A1

WO2025031957A1 - Cartridge for use in an aerosol-generating device

Info

Publication number: WO2025031957A1
Application number: PCT/EP2024/071933
Authority: WO
Inventors: Catalin Marian CHISCOP; Wanjiang Han; Filip Tack
Original assignee: Philip Morris Products S.A.
Priority date: 2023-08-10
Filing date: 2024-08-01
Publication date: 2025-02-13

Abstract

A cartridge (10) for use in an aerosol-generating device (600), the cartridge (10) comprising: a housing (100) having an inlet (110) and an outlet (120), and a chamber (400) between the inlet (110) and the outlet (120); a shredded aerosol-generating substrate (300) within the chamber (400), the aerosol-generating substrate (300) comprising aerosol former and at least one of tobacco and nicotine; and a planar heating element (200) extending into the chamber (400). The planar heating element (200) comprises one or more planar heating surfaces for heating the shredded aerosol-generating substrate (300) to form an aerosol. The density of the shredded aerosol-generating substrate (300) within the chamber (400) of the cartridge (10) is at least 0.1 milligram per cubic millimetre of the chamber (400).

Description

CARTRIDGE FOR USE IN AN AEROSOL-GENERATING DEVICE

The present invention relates to a cartridge for use in an aerosol-generating device, the cartridge comprising an aerosol-generating substrate adapted to produce an inhalable aerosol upon heating.

Aerosol-generating articles in which an aerosol-generating substrate, such as a tobaccocontaining substrate, is heated rather than combusted, are known in the art. Typically, in such heated smoking articles an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the aerosol-generating substrate by heat transfer from the heat source and are entrained in air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol.

A number of prior art documents disclose aerosol-generating devices for consuming aerosol-generating articles. Such devices include, for example, electrically heated aerosolgenerating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of a heated aerosol-generating article. For example, electrically heated aerosol-generating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosol-generating substrate.

Use of an aerosol-generating article in combination with an external heating system is also known. For example, WO 2020/1 15151 describes the provision of one or more heating elements arranged around the periphery of the aerosol-generating article when the aerosol-generating article is received in a cavity of the aerosol-generating device. As an alternative, inductively heatable aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosol-generating substrate have been proposed by WO 2015/176898.

Certain types of aerosol-generating substrates containing nicotine and a relatively high aerosol former content are known, for example, nicotine containing gels and films. Such substrates are typically very stable during storage and advantageously provide a very consistent delivery of nicotine to the consumer upon heating. They can also advantageously generate aerosol at a lower temperature than other solid substrates. However, the use of aerosolgenerating substrates of this type can also present issues. The relatively high aerosol former content increases the risk of leakage of aerosol former from the substrate during storage as well as during use. In addition, certain substrates such as gel compositions will commonly melt upon heating of the aerosol-generating substrate within an aerosol-generating device during use. The viscosity of the gel composition therefore decreases significantly and it can become more difficult to control the movement of the gel composition and in particular, to retain it within the aerosol- generating article. The leakage of aerosol former or melted gel composition from the aerosolgenerating article is undesirable, since it can leak into the heating chamber of the aerosolgenerating device and potentially contaminate the aerosol-generating device. The leakage of aerosol former or gel composition may also be potentially unpleasant for the consumer.

It would therefore be desirable to provide a novel aerosol-generating article having an arrangement that provides improved retention of the aerosol-generating substrate within the aerosol-generating article during storage and use. It would be further desirable to provide such an aerosol-generating article that enables the aerosol-generating substrate to be efficiently heated so that aerosol can be generated from the aerosol-generating substrate in an efficient and consistent way.

The present disclosure relates to a cartridge for use in an aerosol-generating device. The cartridge may comprise a housing having an inlet and an outlet, and a chamber between the inlet and the outlet. The cartridge may further comprise a shredded aerosol-generating substrate within the chamber. The shredded aerosol-generating substrate may comprise at least one aerosol former and at least one of tobacco and nicotine. The cartridge may further comprise a planar heating element extending into the chamber. The planar heating element may comprise one or more planar heating surfaces for heating the shredded aerosol-generating substrate to form an aerosol. The density of the shredded aerosol-generating substrate within the chamber of the cartridge may be at least 0.1 milligram per cubic millimetre of the chamber.

The present invention is defined in the claims set out below.

According to the present invention there is provided a cartridge for use in an aerosolgenerating device, the cartridge comprising: a housing having an inlet and an outlet, and a chamber between the inlet and the outlet; a shredded aerosol-generating substrate within the chamber, the aerosol-generating substrate comprising aerosol former and at least one of tobacco and nicotine; and a planar heating element extending into the chamber, wherein the planar heating element comprises one or more planar heating surfaces for heating the shredded aerosolgenerating substrate material to form an aerosol and wherein the density of the shredded aerosolgenerating substrate within the chamber of the cartridge is at least 0.1 milligram per cubic millimetre of the chamber.

According to the present invention there is further provided a cartridge for use in an aerosolgenerating device, the cartridge comprising: a housing having an inlet and an outlet, and a chamber between the inlet and the outlet; a shredded aerosol-generating substrate within the chamber, the aerosol-generating substrate comprising aerosol former and at least one of tobacco and nicotine; and a planar heating element extending at least partially around the chamber, wherein the planar heating element comprises one or more planar heating surfaces for heating the shredded aerosol-generating substrate material to form an aerosol and wherein the density of the shredded aerosol-generating substrate within the chamber of the cartridge is at least 0.1 milligram per cubic millimetre of the chamber.

As used herein, the term “aerosol-generating device” refers to a device comprising a heater element that interacts with the aerosol-generating substrate of the aerosol-generating article to generate an aerosol.

As used herein, the term “cartridge” relates to a component that interacts with an aerosolforming device to generate an aerosol.

As used herein, the term “aerosol-generating substrate” denotes a substrate capable of releasing volatile compounds upon heating to generate an aerosol.

As used herein, the term “heating element” refers to a component which transfers heat energy to the liquid aerosol-forming substrate.

As used herein, the term “shredded” describes an aerosol-generating substrate that is in the form of a plurality of shreds or strips. In general, the shredded aerosol-generating substrate is formed by the cutting or shredding of a larger portion of the aerosol-generating substrate, such as a sheet, leaf or other piece of plant material. The individual strips or strands are typically elongate in form, with a length that is greater than the width and thickness.

The cartridge according to the present invention contains a shredded aerosol-generating substrate within the chamber of the housing. The shredded aerosol-generating substrate is provided within the chamber so that it is at least partially in contact with the planar heating surfaces of the planar heating element mounted within the chamber. During use, the planar heating element therefore heats the shredded aerosol-generating substrate in order to generate an inhalable aerosol from the substrate.

The cartridge provides a convenient way to store and heat the shredded aerosolgenerating substrate. The chamber of the housing can be readily filled with the shredded aerosolgenerating substrate and provides an effective way to store the aerosol-generating substrate prior to use. The cartridge includes an integrated heating element which is arranged in contact with the shredded aerosol-generating substrate for efficient heating of the aerosol-generating substrate. The planar form of the heating element with one or more planar heating surfaces provides a relatively high surface area over which the aerosol-generating substrate can be directly heated. The shredded form of the aerosol-generating substrate enables the contact between the aerosol-generating substrate and the planar heating surfaces to be optimised.

The provision of shredded aerosol-generating substrate having a density of at least 0.1 milligrams per cubic millimetre of the chamber enables the amount of aerosol-generating substrate in contact with, or in close proximity to, the heating element to be maximised, whilst also allowing sufficient airflow through the cartridge, without an undesirably high level of resistance to draw (RTD). The cartridge therefore advantageously enables a balance to be achieved between optimisation of the efficiency of aerosol generation from the shredded aerosolgenerating substrate and maintenance of an acceptable level of RTD.

According to the present invention, the density of the shredded aerosol-generating substrate within the chamber of the cartridge is at least 0.1 milligrams per cubic millimetre of the chamber. Preferably, the density of the shredded aerosol-generating substrate within the chamber of the cartridge is at least 0.2 milligrams per cubic millimetre of the chamber, more preferably at least 0.3 milligrams per cubic millimetre of the chamber, more preferably at least 0.4 milligrams per cubic millimetres of the chamber, more preferably at least 0.5 milligrams per cubic millimetres of the chamber.

Preferably, the density of the shredded aerosol-generating substrate within the chamber of the cartridge is less than 1 milligram per cubic millimetre of the chamber, more preferably less than 0.9 milligrams per cubic millimetre of the chamber, more preferably less than 0.8 milligrams per cubic millimetre of the chamber, more preferably less than 0.7 milligrams per cubic millimetre of the chamber, more preferably less than 1 milligram per cubic millimetre of the chamber.

For example, the density of the shredded aerosol-generating substrate within the chamber of the cartridge may correspond to between 0.1 milligrams per cubic millimetre and 1 milligram per cubic millimetre of the chamber, or between 0.2 milligrams per cubic millimetre and 0.9 milligrams per cubic millimetre of the chamber, or between 0.3 milligrams per cubic millimetre and 0.8 milligrams per cubic millimetre of the chamber, or between 0.4 milligrams per cubic millimetre and 0.7 milligrams per cubic millimetre of the chamber, or between 0.5 milligrams per cubic millimetre and 0.7 milligrams per cubic millimetre of the chamber.

As used herein, the term “density” refers to the bulk density of the shredded aerosolgenerating substrate within the chamber. The density is calculated by dividing the total mass of the shredded aerosol-generating substrate and dividing it by the total volume of the chamber. The density therefore corresponds to the weight of shredded aerosol-generating substrate per unit volume of the chamber. This is different to the density of the aerosol-generating substrate itself.

At least a portion of the shredded aerosol-generating substrate within the chamber will be in direct contact with the one or more planar heater surfaces. Preferably, the shredded aerosolgenerating substrate is configured to be in direct contact with the one or more planar heating surfaces over a total surface area that corresponds to at least 35 percent of the total cross- sectional area of the chamber in the plane in which the planar heating element extends. This means that the ratio between the total surface area over which the shredded aerosol-generating substrate is in direct contact with the planar heating surfaces and the total cross-sectional area of the chamber in the plane of the planar heater is at least 0.35.

Preferably, the shredded aerosol-generating substrate is configured to be in direct contact with the one or more planar heating surfaces over a total surface area that corresponds to at least 40 percent and preferably at least 45 percent of the total cross-sectional area of the chamber in the plane in which the planar heating element extends. The degree of direct contact between the shredded aerosol-generating substrate and the planar heating surfaces is therefore maximised, in order to maximise the efficiency of heating of the shredded aerosol-generating substrate and therefore the efficiency of aerosol generation from the substrate during use.

For the purposes of the present invention, a shredded aerosol-generating substrate (or a portion thereof) is in ‘direct contact’ with the planar heating surface if the substrate is touching a portion of the planar heating surface that is heated during use, with no space or intervening material in between. As a result of this direct contact, heat can be transferred directly from the planar heating surface to the contacting portion of the shredded aerosol-generating substrate.

Preferably, the shredded aerosol-generating substrate is in direct contact with the planar heating surfaces over a total area of at least 40 square millimetres, more preferably at least 45 square millimetres, more preferably at least 50 square millimetres, more preferably at least 55 square millimetres, more preferably at least 60 square millimetres. The shredded aerosolgenerating substrate may be in direct contact with the planar heating surfaces over a total area of up to 120 square millimetres, or up to 110 square millimetres, or up to 100 square millimetres.

For example, the shredded aerosol-generating substrate may be in direct contact with the planar heating surfaces over a total area of between 40 square millimetres and 120 square millimetres, or between 45 square millimetres and 120 square millimetres, or between 50 square millimetres and 1 10 square millimetres, or between 55 square millimetres and 1 10 square millimetres, or between 60 square millimetres and 100 square millimetres.

The chamber of the cartridge preferably contains at least 100 milligrams of the shredded aerosol-generating substrate, more preferably at least 125 milligrams of the shredded aerosolgenerating substrate, more preferably at least 150 milligrams of the shredded aerosol-generating substrate. The chamber of the cartridge may contain up to 300 milligrams of the shredded aerosol-generating substrate, or up to 275 milligrams of the shredded aerosol-generating substrate, or up to 250 milligrams of the shredded aerosol-generating substrate. For example, the chamber of the cartridge may contain between 100 milligrams and 300 milligrams of the shredded aerosol-generating substrate, or between 125 milligrams and 275 milligrams of the shredded aerosol-generating substrate, or between 150 milligrams and 250 milligrams of the shredded aerosol-generating substrate.

The percentage fill of the chamber by the shredded aerosol-generating substrate is preferably at least 50 percent, more preferably at least 60 percent, more preferably at least 70 percent. The percentage fill is preferably less than 90 percent. The percentage fill corresponds to the percentage of the chamber of the cartridge that is occupied by the shredded aerosolgenerating substrate. It may be advantageous to retain some empty space within the chamber to allow for air flow through the chamber and for the shredded aerosol-generating substrate to be heated evenly.

The shredded aerosol-generating substrate is preferably provided directly in the chamber of the cartridge. However, alternatively, the shredded aerosol-generating substrate may be provided within one or more permeable containers, such as one or more permeable pouches.

The shredded aerosol-generating substrate preferably has a cut width of at least 0.3 millimetres, more preferably at least 0.4 millimetres, more preferably at least 0.5 millimetres, more preferably at least 0.6 millimetres. Preferably, the shredded aerosol-generating substrate has a cut width of less than 2 millimetres, more preferably less than 1 .75 millimetres, more preferably less than 1.5 millimetres, more preferably less than 1.25 millimetre, more preferably less than 1 millimetre.

For example, the cut width of the shredded aerosol-generating substrate may be between 0.3 millimetres and 2 millimetres, or between 0.4 millimetres and 1 .75 millimetres, or between 0.5 millimetres and 1.5 millimetres, or between 0.6 millimetres and 1 millimetre.

The cut width of the shredded aerosol-generating substrate may play a role in the distribution of heat inside the cartridge. Also, the cut width may play a role in the resistance to draw of the cartridge. Further, the cut width may impact the overall density of the aerosolgenerating substrate as a whole.

As defined above, the shredded aerosol-generating substrate comprises at least one aerosol former and at least one of nicotine and tobacco. The shredded aerosol-generating substrate may have a variety of different forms and compositions.

The aerosol former may be any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol. Suitable aerosol formers are for example: polyhydric alcohols such as, for example, triethylene glycol, 1 ,3-butanediol, propylene glycol and glycerine; esters of polyhydric alcohols such as, for example, glycerol mono-, di- or triacetate; aliphatic esters of mono-, di- or polycarboxylic acids such as, for example, dimethyl dodecanedioate and dimethyl tetradecanedioate; and combinations thereof.

Preferably, the aerosol former comprises one or more of glycerin and propylene glycol. The aerosol former may consist of glycerin or propylene glycol or of a combination of glycerin and propylene glycol.

In certain embodiments, the aerosol-generating substrate preferably comprises at least 5 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably at least 10 percent by weight on a dry weight basis, more preferably at least 15 percent by weight on a dry weight basis. In such embodiments, the aerosol-generating substrate preferably comprises no more than 30 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably no more than 25 percent by weight on a dry weight basis, more preferably no more than 20 percent by weight on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate may be between 5 percent and 30 percent by weight, or between 10 percent and 25 percent by weight, or between about 15 percent and about 20 percent by weight, on a dry weight basis. In such embodiments, the aerosol former content is therefore relatively low.

In other embodiments, the aerosol-generating substrate preferably comprises at least 40 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably at least 45 percent by weight on a dry weight basis, more preferably at least 50 percent by weight on a dry weight basis. In such embodiments, the aerosol-generating substrate preferably comprises no more than 80 percent by weight of aerosol former on a dry weight basis of the aerosol-generating substrate, more preferably no more than 75 percent by weight on a dry weight basis, more preferably no more than 70 percent by weight on a dry weight basis. For example, the aerosol former content of the aerosol-generating substrate may be between 40 percent and 80 percent by weight, or between 45 percent and 75 percent by weight, or between about 50 percent and about 70 percent by weight, on a dry weight basis. In such embodiments, the aerosol former content is therefore relatively high.

The aerosol-generating substrate further comprises at least one of tobacco and nicotine. The aerosol-generating substrate may comprise tobacco, which intrinsically contains nicotine. For example, the aerosol-generating substrate may be a tobacco cut filler, or a homogenised tobacco material, as described in more detail below. Alternatively or in addition, the aerosolgenerating substrate may comprise extrinsic nicotine, which is nicotine that is added as a specific component, separate from any tobacco plant material. In some embodiments, the aerosolgenerating substrate may be substantially free from tobacco, or tobacco free.

As used herein with reference to the invention, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt. In embodiments in which the aerosol-generating substrate comprises a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

The aerosol-generating substrate may comprise natural nicotine or synthetic nicotine.

The nicotine may comprise one or more nicotine salts. The one or more nicotine salts may be selected from the list consisting of nicotine lactate, nicotine citrate, nicotine pyruvate, nicotine bitartrate, nicotine benzoate, nicotine pectate, nicotine alginate, and nicotine salicylate.

The nicotine may comprise an extract of tobacco.

Preferably, the aerosol-generating substrate comprises at least 0.5 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-generating substrate comprises at least 1 percent by weight of nicotine on a dry weight basis. Even more preferably, the aerosolgenerating substrate comprises at least 2 percent by weight of nicotine on a dry weight basis. In addition, or as an alternative, the aerosol-generating substrate preferably comprises less than 10 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-generating substrate comprises less than 8 percent by weight of nicotine on a dry weight basis. More preferably, the aerosol-generating substrate comprises less than 6 percent by weight of nicotine on a dry weight basis.

For example, the aerosol-generating substrate may comprise between 0.5 percent and 10 percent by weight of nicotine, or between 1 percent and 8 percent by weight of nicotine, or between 2 percent and 6 percent by weight of nicotine, on a dry weight basis.

The aerosol-forming substrate may comprise one or more carboxylic acids. Advantageously, including one or more carboxylic acids in the aerosol-forming substrate may create a nicotine salt.

The one or more carboxylic acids comprise one or more of lactic acid and levulinic acid. Advantageously, the present inventors have found that lactic acid and levulinic acid are particularly good carboxylic acids for creating nicotine salts.

Preferably, the aerosol-forming substrate comprises at least 0.5 percent by weight of carboxylic acid, on a dry weight basis. More preferably, the aerosol-forming substrate comprises at least 1 percent by weight of carboxylic acid, on a dry weight basis. More preferably, the aerosolforming substrate comprises at least 2 percent by weight of carboxylic acid, on a dry weight basis.

In addition, or as an alternative, the aerosol-generating substrate preferably comprises less than 15 percent by weight of carboxylic acid, on a dry weight basis. More preferably, the aerosol-generating substrate preferably comprises less than 10 percent by weight of carboxylic acid, on a dry weight basis. More preferably, the aerosol-generating substrate preferably comprises less than 5 percent by weight of carboxylic acid, on a dry weight basis. For example, the aerosol-generating substrate may comprise between 0.5 percent and 15 percent by weight of carboxylic acid, or between 1 percent and 10 percent by weight of carboxylic acid, or between 2 percent and 5 percent by weight of carboxylic acid.

As defined above, the aerosol-generating substrate in the cartridge of the present invention is in a shredded form. For example, the shredded aerosol-generating substrate may be in the form of shredded tobacco material, such as cut filler. Alternatively, the shredded aerosolgenerating substrate may be in the form of a shredded sheet of homogenised plant material, such as a homogenised tobacco material. Alternatively, the shredded aerosol-generating substrate may be in the form of a shredded non-tobacco material, as described in more detail below.

In certain preferred embodiments of the present invention, the shredded aerosolgenerating substrate is cut filler. Within the context of the present specification, the term “cut filler” is used to describe to a blend of shredded plant material, such as tobacco plant material, including, in particular, one or more of leaf lamina, processed stems and ribs, homogenised plant material.

The cut filler may also comprise other after-cut, filler tobacco or casing. Preferably, the cut filler comprises at least 25 percent of plant leaf lamina, more preferably, at least 50 percent of plant leaf lamina, still more preferably at least 75 percent of plant leaf lamina and most preferably at least 90 percent of plant leaf lamina. Preferably, the plant material is one of tobacco, mint, tea and cloves. Most preferably, the plant material is tobacco.

Preferably, the cut filler comprises tobacco plant material comprising lamina of one or more of bright tobacco, dark tobacco, aromatic tobacco and filler tobacco. With reference to the present invention, the term “tobacco” describes any plant member of the genus Nicotiana.

The cut filler suitable to be used with the present invention generally may resemble cut filler used for conventional smoking articles. The cut width of the cut filler is preferably within the ranges defined above. For example, the cut width of the cut filler may be between 0.3 millimetres and 2 millimetres, or between 0.4 millimetres and 1 .75 millimetres, or between 0.5 millimetres and 1.5 millimetres, or between 0.6 millimetres and 1 millimetre.

The strand length of the cut filler is to some extent a random value as the length of the strands will depend on the overall size of the object that the strand is cut off from. Nevertheless, by conditioning the material before cutting, for example by controlling the moisture content and the overall subtlety of the material, longer strands can be cut. Preferably, the strands have a length of between about 10 millimetres and about 40 millimetres.

Preferably, the cut filler is soaked with aerosol former. Soaking the cut filler can be done by spraying or by other suitable application methods. The aerosol former may be applied to the blend during preparation of the cut filler. For example, the aerosol former may be applied to the blend in the direct conditioning casing cylinder (DCCC). Conventional machinery can be used for applying an aerosol former to the cut filler. Suitable aerosol formers are described below.

The cut filler preferably comprises between 5 percent and 20 percent of aerosol former by weight on a dry weight basis, more preferably between 10 percent and 18 percent by weight on a dry weight basis, more preferably between 12 percent and 15 percent by weight on a dry weight basis.

In certain embodiments, the shredded aerosol-generating substrate comprises shredded homogenised plant material, preferably shredded homogenised tobacco material.

As used herein, the term “homogenised plant material” encompasses any plant material formed by the agglomeration of particles of plant. For example, sheets or webs of homogenised tobacco material for the aerosol-generating substrates of the present invention may be formed by agglomerating particles of tobacco material obtained by pulverising, grinding or comminuting plant material and optionally one or more of tobacco leaf lamina and tobacco leaf stems. The homogenised plant material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art. The aerosol former content of the homogenised tobacco material is preferably within the ranges defined above for aerosol-generating substrate having a relatively low aerosol former content.

The homogenised plant material preferably further comprises at least one exogenous binder. Suitable exogenous binders would be known to the skilled person and include but are not limited to: gums such as, for example, guar gum, xanthan gum, arabic gum and locust bean gum; cellulosic binders such as, for example, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose and ethyl cellulose; polysaccharides such as, for example, starches, organic acids, such as alginic acid, conjugate base salts of organic acids, such as sodium-alginate, agar and pectins; and combinations thereof. Preferably, the binder comprises guar gum.

The binder may be present in an amount of from about 1 percent to about 10 percent by weight, based on the dry weight of the homogenised plant material, preferably in an amount of from about 2 percent to about 5 percent by weight, based on the dry weight of the homogenised plant material.

In other preferred embodiments, the aerosol-generating substrate comprises a shredded aerosol-generating film comprising a cellulosic based film forming agent, nicotine and the aerosol former. The aerosol-generating film may further comprise a cellulose based strengthening agent. The aerosol-generating film may further comprise water, preferably 30 percent by weight of less of water.

As used herein, the term “film” is used to describe a solid laminar element having a thickness that is less than the width or length thereof. The film may be self-supporting. In other words, a film may have cohesion and mechanical properties such that the film, even if obtained by casting a film-forming formulation on a support surface, can be separated from the support surface. Such a film may be directly shredded to form the aerosol-generating substrate of the present invention. Alternatively, the film may be disposed on a support or sandwiched between other materials. This may enhance the mechanical stability of the film. The combined film and support may be shredded to provide the aerosol-generating substrate of the present invention.

The cut width of the shredded aerosol-generating film is preferably within the ranges defined above. For example, the cut width of the shredded aerosol-generating film may be between 0.3 millimetres and 2 millimetres, or between 0.4 millimetres and 1 .75 millimetres, or between 0.5 millimetres and 1.5 millimetres, or between 0.6 millimetres and 1 millimetre.

The aerosol former content of the aerosol-generating film is within the ranges defined above for aerosol-generating substrates having a relatively high aerosol former content.

In the context of the present invention the term “cellulose based film-forming agent” is used to describe a cellulosic polymer capable, by itself or in the presence of an auxiliary thickening agent, of forming a continuous film. Preferably, the cellulose based film-forming agent is selected from the group consisting of hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethyl methyl cellulose (HEMC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and combinations thereof. In particularly preferred embodiments, the cellulose based film-forming agent is HPMC.

The aerosol-generating film may have a cellulose based film-forming agent content of between 10 percent and 40 percent by weight, or between 15 percent and 35 percent by weight, or between 20 percent and 30 percent by weight, on a dry weight basis.

Preferably, the aerosol-generating film further comprises a cellulose based strengthening agent. Preferably, the cellulose based strengthening agent is selected from the group consisting of cellulose fibres, microcrystalline cellulose (MCC), cellulose powder, and combinations thereof.

The aerosol-generating film may have a cellulose based strengthening agent content of between 0.5 percent and 40 percent by weight on a dry weight basis, or between 5 percent and 30 percent by weight on a dry weight basis, or between 10 percent and 25 percent by weight on a dry weight basis.

The aerosol-generating film may further comprise a carboxymethyl cellulose, preferably sodium carboxymethyl cellulose. The aerosol-generating film may have a carboxymethyl cellulose content of between 1 percent and 15 percent by weight, or between 2 percent and 12 percent by weight, or between 4 percent and 10 percent by weight on a dry weight basis.

The aerosol-generating film preferably comprises nicotine. As used herein with reference to the invention, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt. In embodiments in which the aerosol-generating film comprises a nicotine base or a nicotine salt, the amounts of nicotine recited herein are the amount of free base nicotine or amount of protonated nicotine, respectively.

The aerosol-generating film may comprise natural nicotine or synthetic nicotine.

The aerosol-generating film may comprise one or more monoprotic nicotine salts. As used herein with reference to the invention, the term “monoprotic nicotine salt” is used to describe a nicotine salt of a monoprotic acid.

Preferably, the aerosol-generating film comprises between 0.5 percent and 10 percent by weight of nicotine, or between 1 percent and 8 percent by weight of nicotine, or between 2 percent and 6 percent by weight of nicotine, on a dry weight basis.

The aerosol-generating film may be a substantially tobacco-free aerosol-generating film.

In preferred embodiments, the aerosol-generating film comprises an acid. More preferably, the aerosol-generating film comprises one or more organic acids. Even more preferably, the aerosol-generating film comprises one or more carboxylic acids. In particularly preferred embodiments, the acid is lactic acid, benzoic acid, fumaric acid or levulinic acid. Preferably, the aerosol-generating film comprises between 0.25 percent and 3.5 percent by weight of an acid, or between 0.5 percent and 3 percent by weight of an acid, or between 1 percent and 2.5 percent by weight of an acid, on a dry weight basis.

The aerosol-generating film may have a thickness from about 0.1 millimetres to about 1 millimetre, more preferably from about 0.1 millimetres to about 0.75 millimetres, even more preferably from about 0.1 millimetres to about 0.5 millimetres. In particularly preferred embodiments, a layer of the film-forming composition is formed that has a thickness from about 50 micrometres to 400 micrometres, more preferably from about 100 micrometres to 200 micrometres.

The aerosol-generating film may optionally be provided on a suitable carrier element.

In alternative embodiments of the invention, the aerosol-generating substrate may comprise a gel composition that includes nicotine, at least one gelling agent and the aerosol former. The gel composition is preferably substantially tobacco free.

The preferred weight ranges for nicotine in the gel composition are the same as those defined above in relation to aerosol-generating films.

The gel composition preferably comprises at least 50 percent by weight of aerosol former, more preferably at least 60 percent by weight, more preferably at least 70 percent by weight of aerosol former, on a dry weight basis. The gel composition may comprise up to 80 percent by weight of aerosol former. The aerosol former in the gel composition is preferably glycerol.

The gel composition preferably includes at least one gelling agent. Preferably, the gel composition includes a total amount of gelling agents in a range from about 0.4 percent by weight to about 10 percent by weight, or from about 0.5 percent by weight to about 8 percent by weight, or from about 1 percent by weight to about 6 percent by weight, or from about 2 percent by weight to about 4 percent by weight, or from about 2 percent by weight to about 3 percent by weight.

The term “gelling agent” refers to a compound that homogeneously, when added to a 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of about 0.3 percent by weight, forms a solid medium or support matrix leading to a gel. Gelling agents include, but are not limited to, hydrogen-bond crosslinking gelling agents, and ionic crosslinking gelling agents.

The term “hydrogen-bond crosslinking gelling agent” refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via hydrogen bonding.

The hydrogen-bond crosslinking gelling agent may include one or more of a galactomannan, gelatin, agarose, or konjac gum, or agar. The hydrogen-bond crosslinking gelling agent may preferably include agar.

The term “ionic crosslinking gelling agent” refers to a gelling agent that forms non-covalent crosslinking bonds or physical crosslinking bonds via ionic bonding. The ionic crosslinking gelling agent may include low acyl gellan, pectin, kappa carrageenan, iota carrageenan or alginate. The ionic crosslinking gelling agent may preferably include low acyl gellan.

The gelling agent may include one or more biopolymers. The biopolymers may be formed of polysaccharides.

Biopolymers include, for example, gellan gums (native, low acyl gellan gum, high acyl gellan gums with low acyl gellan gum being preferred), xanthan gum, alginates (alginic acid), agar, guar gum, and the like. The composition may preferably include xanthan gum. The composition may include two biopolymers. The composition may include three biopolymers. The composition may include the two biopolymers in substantially equal weights. The composition may include the three biopolymers in substantially equal weights.

The gel composition may further include a viscosifying agent. The viscosifying agent combined with the hydrogen-bond crosslinking gelling agent and the ionic crosslinking gelling agent appears to surprisingly support the solid medium and maintain the gel composition even when the gel composition comprises a high level of glycerol.

The term “viscosifying agent” refers to a compound that, when added homogeneously into a 25°C, 50 percent by weight water/50 percent by weight glycerol mixture, in an amount of 0.3 percent by weight., increases the viscosity without leading to the formation of a gel, the mixture staying or remaining fluid.

The gel composition preferably includes the viscosifying agent in a range from about 0.2 percent by weight to about 5 percent by weight, or from about 0.5 percent by weight to about 3 percent by weight, or from about 0.5 percent by weight to about 2 percent by weight, or from about 1 percent by weight to about 2 percent by weight.

The viscosifying agent may include one or more of xanthan gum, carboxymethyl-cellulose, microcrystalline cellulose, methyl cellulose, gum Arabic, guar gum, lambda carrageenan, or starch. The viscosifying agent may preferably include xanthan gum.

The gel composition may further include a divalent cation. Preferably the divalent cation includes calcium ions, such as calcium lactate in solution. Divalent cations (such as calcium ions) may assist in the gel formation of compositions that include gelling agents such as the ionic crosslinking gelling agent, for example. The ion effect may assist in the gel formation. The divalent cation may be present in the gel composition in a range from about 0.1 to about 1 percent by weight, or about 0.5 percent by weight.

The gel composition may further include an acid. The acid may comprise a carboxylic acid. The carboxylic acid may include a ketone group. Preferably the carboxylic acid may include a ketone group having less than about 10 carbon atoms, or less than about 6 carbon atoms or less than about 4 carbon atoms, such as levulinic acid or lactic acid. Preferably this carboxylic acid has three carbon atoms (such as lactic acid). The gel composition preferably comprises some water. The gel composition is more stable when the composition comprises some water.

Preferably the gel composition comprises between about 8 percent by weight to about 32 percent by weight water, or from about 15 percent by weight to about 25 percent by weight water, or from about 18 percent by weight to about 22 percent by weight water, or about 20 percent by weight water.

The gel composition may optionally be provided on a suitable carrier element. The combination of the gel composition and the carrier element may be shredded to provide the aerosol-generating substrate of the present invention.

The cut width of the shredded gel composition (with or without the carrier element) is preferably within the ranges defined above. For example, the cut width of the shredded gel composition may be between 0.3 millimetres and 2 millimetres, or between 0.4 millimetres and 1.75 millimetres, or between 0.5 millimetres and 1.5 millimetres, or between 0.6 millimetres and 1 millimetre.

In some embodiments of the present invention, the shredded aerosol-generating substrate within the chamber of the cartridge may all have substantially the same composition.

In other embodiments of the present invention, the cartridge may contain a first shredded aerosol-generating substrate and a second shredded aerosol-generating substrate having a different composition to the first shredded aerosol-generating substrate. The use of two or more different aerosol-generating substrates in the cartridge according to the present invention can advantageously enable the aerosol generated from the cartridge to be tailored to provide an improved aerosol delivery to the consumer. For example, the compositions of the first and second shredded aerosol-generating substrates may be different from each other such that the aerosolgenerating substrates release aerosol at a slightly different time to each other, or release aerosols having different flavours to each other.

The first and second shredded aerosol-generating substrates may be provided with a different level of aerosol former to each other. For example, the first shredded aerosol-generating substrate may have an aerosol former content that is at least 2 percent higher than the aerosol former content of the second shredded aerosol-generating substrate, more preferably at least 5 percent higher. Alternatively or in addition, the first and second aerosol-generating substrate may be provided with a different type of aerosol former, which may cause the aerosols from the respective substrates to be released at slightly different times to each other.

The first and second shredded aerosol-generating substrates may be provided with a different level of tobacco or nicotine to each other. Alternatively or in addition, the first and second shredded aerosol-generating substrates may be provided with different additives to each other, in order to tailor the sensory properties of the aerosols generated from the respective substrates. For example, the first and second aerosol-generating substrates may comprise different flavourants to each other.

The first and second shredded aerosol-generating substrates may have a different cut width to each other.

The first and second shredded aerosol-generating substrates may be different types of aerosol-generating substrate, for example, the first and second aerosol-generating substrates may be different substrates selected from homogenised plant material, aerosol-generating film and gel composition.

Where the housing of the cartridge comprises first and second shredded aerosol-generating substrates having a different composition to each other, these may be provided on opposed sides of the planar heating element, in different portions of the housing, as described in more detail below.

The cartridge according to the present invention comprises a housing which contains the shredded aerosol-generating substrate. According to the invention, the housing comprises an inlet and an outlet and a chamber between the inlet and outlet, wherein the shredded aerosolgenerating substrate is contained within the chamber. During use, the inlet and outlet define one or more airflow pathways through the chamber, such that air can be drawn through the chamber during use in order to optimise the heating of the shredded aerosol-generating substrate.

The housing may be a rigid housing. The housing may be formed from a rigid material.

The housing may comprise an upstream portion. The housing may comprise a downstream portion. The housing may comprise a body.

The upstream portion may be removably attachable to the body. The downstream portion may be removably attachable to the body. The upstream portion may be fixed to the body. The downstream portion may be fixed to the body.

The chamber may extend between the upstream portion and the downstream portion. The chamber may be defined by the upstream portion, the downstream portion, and the body.

The upstream portion may be located at an upstream end of the cartridge.

The upstream portion may comprise the inlet. The upstream portion may comprise an upstream end cap.

The upstream portion may have a length of at least 3 millimetres. The upstream portion may have a length of at least 3.5 millimetres. The upstream portion may have a length of at least 4 millimetres.

The upstream portion may have a length of less than or equal to 4.5 millimetres. The upstream portion may have a length of less than or equal to 4 millimetres. The upstream portion may have a length of less than or equal to 3.5 millimetres.

The upstream portion may have a length of between 3 millimetres and 4.5 millimetres.

The upstream portion may extend into the body. The upstream portion may have an external volume of at least 140 cubic millimetres. The upstream portion may have an external volume of at least 145 cubic millimetres. The upstream portion may have an external volume of at least 150 cubic millimetres.

The upstream portion may have an external volume of less than or equal to 160 cubic millimetres. The upstream portion may have an external volume of less than or equal to 155 cubic millimetres. The upstream portion may have an external volume of less than or equal to 150 cubic millimetres.

The upstream portion may have an external volume of between 140 cubic millimetres and 160 cubic millimetres. The upstream portion may have an external volume of between 145 cubic millimetres and 155 cubic millimetres.

The downstream portion may be located at a downstream end of the cartridge.

The downstream portion may comprise the outlet. The downstream portion may comprise a downstream end cap.

The downstream portion may have a length of at least 2.5 millimetres. The downstream portion may have a length of at least 3 millimetres. The downstream portion may have a length of at least 3.5 millimetres.

The downstream portion may have a length of less than or equal to 4 millimetres. The downstream portion may have a length of less than or equal to 3.5 millimetres. The downstream portion may have a length of less than or equal to 3 millimetres.

The downstream portion may have a length of between 2.5 millimetres and 4 millimetres.

The downstream portion may extend into the body. The downstream portion may extend into the body and the chamber may comprise a downstream cavity defined by the downstream portion.

The downstream portion may have an external volume of at least 90 cubic millimetres. The downstream portion may have an external volume of at least 95 cubic millimetres. The downstream portion may have an external volume of at least 100 cubic millimetres.

The downstream portion may have an external volume of less than or equal to 1 10 cubic millimetres. The downstream portion may have an external volume of less than or equal to 105 cubic millimetres. The downstream portion may have an external volume of less than or equal to 100 cubic millimetres.

The downstream portion may have an external volume of between 90 cubic millimetres and 110 cubic millimetres. The downstream portion may have an external volume of between 95 cubic millimetres and 105 cubic millimetres.

The downstream cavity may have an internal volume of at least 70 cubic millimetres. The downstream cavity may have an internal volume of at least 75 cubic millimetres. The downstream cavity may have an internal volume of at least 80 cubic millimetres. The downstream cavity may have an internal volume of less than or equal to 90 cubic millimetres. The downstream cavity may have an internal volume of less than or equal to 85 cubic millimetres. The downstream cavity may have an internal volume of less than or equal to 80 cubic millimetres.

The downstream cavity may have an internal volume of between 70 cubic millimetres and 90 cubic millimetres. The downstream cavity may have an internal volume of between 75 cubic millimetres and 85 cubic millimetres.

The downstream cavity may comprise a first section on the first side of the heating element and a second section on the second side of the heating element.

The first section of the downstream cavity may have an internal volume of at least 30 cubic millimetres. The first section of the downstream cavity may have an internal volume of at least 35 cubic millimetres. The first section of the downstream cavity may have an internal volume of at least 40 cubic millimetres.

The first section of the downstream cavity may have an internal volume of less than or equal to 50 cubic millimetres. The first section of the downstream cavity may have an internal volume of less than or equal to 45 cubic millimetres. The first section of the downstream cavity may have an internal volume of less than or equal to 40 cubic millimetres.

The first section of the downstream cavity may have an internal volume of between 30 cubic millimetres and 50 cubic millimetres. The first section of the downstream cavity may have an internal volume of between 35 cubic millimetres and 45 cubic millimetres.

The second section of the downstream cavity may have an internal volume of at least 30 cubic millimetres. The second section of the downstream cavity may have an internal volume of at least 35 cubic millimetres. The second section of the downstream cavity may have an internal volume of at least 40 cubic millimetres.

The second section of the downstream cavity may have an internal volume of less than or equal to 50 cubic millimetres. The second section of the downstream cavity may have an internal volume of less than or equal to 45 cubic millimetres. The second section of the downstream cavity may have an internal volume of less than or equal to 40 cubic millimetres.

The second section of the downstream cavity may have an internal volume of between 30 cubic millimetres and 50 cubic millimetres. The second section of the downstream cavity may have an internal volume of between 35 cubic millimetres and 45 cubic millimetres.

The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of at least 70 cubic millimetres. The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of at least 75 cubic millimetres. The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of at least 80 cubic millimetres. The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of less than or equal to 90 cubic millimetres. The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of less than or equal to 85 cubic millimetres. The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of less than or equal to 80 cubic millimetres.

The first section of the downstream cavity and the second section of the downstream cavity may have a combined internal volume of between 70 cubic millimetres and 90 cubic millimetres.

The body may extend between the upstream portion and the downstream portion.

The body may define the chamber. The body may define the chamber between the upstream portion and the downstream portion.

The body may have an external length of at least 16 millimetres. The body may have an external length of at least 16.5 millimetres. The body may have an external length of at least 17 millimetres.

The body may have an external length of less than or equal to 18 millimetres. The body may have an external length of less than or equal to 17.5 millimetres. The body may have an external length of less than or equal to 17 millimetres.

The body may have an external length of between 16 millimetres and 18 millimetres.

The body may have an external width of at least 11 .5 millimetres. The body may have an external width of at least 12 millimetres.

The body may have an external width of less than or equal to 13 millimetres. The body may have an external width of less than or equal to 12.5 millimetres. The body may have an external width of less than or equal to 12 millimetres.

The body may have an external width of between 11 .5 millimetres and 13 millimetres.

The body may have an external depth of at least 5 millimetres. The body may have an external depth of at least 5.5 millimetres. The body may have an external depth of at least 6 millimetres.

The body may have an external depth of less than or equal to 6.5 millimetres. The body may have an external depth of less than or equal to 6 millimetres. The body may have an external depth of less than or equal to 5.5 millimetres.

The body may have an external depth of between 5 millimetres and 6.5 millimetres.

The body may have an internal cross-sectional area of between 40 square millimetres and 80 square millimetres.

The body may have an internal cross-sectional area of between 10 square millimetres and 300 square millimetres. The body may have an internal cross-sectional area of between 15 square millimetres and 260 square millimetres. The body may have an internal cross-sectional area of between 20 square millimetres and 220 square millimetres. The body may have an internal cross- sectional area of between 25 square millimetres and 180 square millimetres. The body may have an internal cross-sectional area of between 30 square millimetres and 160 square millimetres. The body may have an internal cross-sectional area of between 35 square millimetres and 120 square millimetres. The body may have an internal cross-sectional area of between 40 square millimetres and 100 square millimetres. The body may have an internal cross-sectional area of between 45 square millimetres and 80 square millimetres. The body may have an internal cross- sectional area of between 50 square millimetres and 70 square millimetres. The body may have an internal cross-sectional area of between 50 square millimetres and 69 square millimetres. The body may have an internal cross-sectional area of between 50 square millimetres and 67 square millimetres. The body may have an internal cross-sectional area of between 50 square millimetres and 65 square millimetres. The body may have an internal cross-sectional area of between 51 square millimetres and 63 square millimetres. The body may have an internal cross-sectional area of between 53 square millimetres and 61 square millimetres. The body may have an internal cross-sectional area of between 55 square millimetres and 59 square millimetres.

The internal cross-sectional area of the body may be taken at an axial cross-section of the body.

The internal cross-sectional area of the body may be taken over at least 50 percent of the length of the body. The internal cross-sectional area of the body may be taken over at least 80 percent of the length of the body. The internal cross-sectional area of the body may be taken over 100 percent of the length of the body.

The body may have an external perimeter of between 30 millimetres and 39 millimetres. The body may have an external perimeter of between 31 millimetres and 38 millimetres. The body may have an external perimeter of between 32 millimetres and 37 millimetres. The body may have an external perimeter of between 33 millimetres and 36 millimetres. The body may have an external perimeter of between 34 millimetres and 35 millimetres.

The external perimeter of the body may be taken at the same point at which the internal cross-sectional area of the body is measured.

The external perimeter of the body may be taken at an axial cross-section of the body.

The external perimeter of the body may be the average external perimeter over at least 50 percent of the body. The external perimeter of the body may be the average external perimeter over at least 80 percent of the body. The external perimeter of the body may be the average external perimeter of the body.

A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.2 and 0.6. A ratio of the external perimeter of the body to the internal cross- sectional area of the body may be between 0.22 and 0.58. A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.24 and 0.56. A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.26 and 0.54. A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.28 and 0.52. A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.3 and 0.5. A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.32 and 0.48. A ratio of the external perimeter of the body to the internal cross-sectional area of the body may be between 0.34 and 0.46.

The body may have an external surface area of between 530 square millimetres and 570 square millimetres. The body may have an external surface area of between 535 square millimetres and 565 square millimetres. The body may have an external surface area of between 540 square millimetres and 560 square millimetres. The body may have an external surface area of between 545 square millimetres and 555 square millimetres.

The body may be tubular.

The downstream portion may comprise a transparent material. The downstream portion may be formed from a transparent material. The downstream portion may comprise a translucent material. The downstream portion may be formed from a translucent material. The downstream portion may comprise a plastic. The downstream portion may comprise a high-temperature plastic. The downstream portion may be formed from liquid crystal polymer; polyetheretherketone; or cyclic olefin copolymer. The downstream portion may be injection moulded.

The upstream portion may comprise a transparent material. The upstream portion may be formed from a transparent material. The upstream portion may comprise a translucent material. The upstream portion may be formed from a translucent material. The upstream portion may comprise a plastic. The upstream portion may comprise a high-temperature plastic. The upstream portion may be formed from liquid crystal polymer; polyetheretherketone; or cyclic olefin copolymer. The upstream portion may be injection moulded.

The body may be formed from a plant material. The body may be formed from a metal. The body may be formed from aluminium. The body may be formed from an alloy. The body may be formed from stainless steel. The body may be formed from a plastic. The body may comprise a high-temperature plastic. The body may be formed from liquid crystal polymer; polyetheretherketone; or cyclic olefin copolymer. The body may be injection moulded.

The housing may have an external volume of between 1300 cubic millimetres and 1500 cubic millimetres. The housing may have an external volume of between 1320 cubic millimetres and 1480 cubic millimetres. The housing may have an external volume of between 1340 cubic millimetres and 1460 cubic millimetres. The housing may have an external volume of between 1360 cubic millimetres and 1440 cubic millimetres. The housing may have an external volume of between 1380 cubic millimetres and 1420 cubic millimetres.

The housing may extend between the inlet and the outlet. The housing may define the chamber. The housing may define the chamber between the inlet and the outlet. The housing may define the chamber between the upstream portion and the downstream portion.

The housing may have an external length of at least 16 millimetres. The housing may have an external length of at least 16.5 millimetres. The housing may have an external length of at least 17 millimetres. The housing may have an external length of at least 17.5 millimetres. The housing may have an external length of at least 17 millimetres. The housing may have an external length of at least 17 millimetres.

The housing may have an external length of less than or equal to 20 millimetres. The housing may have an external length of less than or equal to 19.5 millimetres. The housing may have an external length of less than or equal to 19 millimetres. The housing may have an external length of less than or equal to 18.5 millimetres. The housing may have an external length of less than or equal to 18 millimetres. The housing may have an external length of less than or equal to 17.5 millimetres. The housing may have an external length of less than or equal to 17 millimetres.

The housing may have an external length of between 16 millimetres and 20 millimetres.

The housing may have an external width of at least 1 1 .5 millimetres. The housing may have an external width of at least 12 millimetres.

The housing may have an external width of less than or equal to 13 millimetres. The housing may have an external width of less than or equal to 12.5 millimetres. The housing may have an external width of less than or equal to 12 millimetres.

The housing may have an external width of between 1 1 .5 millimetres and 13 millimetres.

The housing may have an external depth of at least 5 millimetres. The housing may have an external depth of at least 5.5 millimetres. The housing may have an external depth of at least 6 millimetres.

The housing may have an external depth of less than or equal to 6.5 millimetres. The housing may have an external depth of less than or equal to 6 millimetres. The housing may have an external depth of less than or equal to 5.5 millimetres.

The housing may have an external depth of between 5 millimetres and 6.5 millimetres.

The inlet may comprise one or more apertures. The inlet may comprise a plurality of apertures.

The outlet may comprise one or more apertures. The outlet may comprise a plurality of apertures.

The housing may comprise an air flow path extending between the inlet and the outlet.

The chamber may be configured to store the aerosol-generating substrate. The chamber may comprise a first portion on a first side of the heating element and a second portion on a second side of the heating element. The aerosol-generating substrate may be disposed within at least one of the first portion and the second portion of the chamber The first portion of the chamber may have an internal volume that is substantially the same as the internal volume of the second portion.

The first portion of the chamber may have a shape that is substantially the same as the shape of the second portion of the chamber.

The first portion of the chamber may have a size that is substantially the same as the size of the second portion of the chamber. The first portion of the chamber may have a length that is substantially the same as the length of the second portion of the chamber. The first portion of the chamber may have a width that is substantially the same as the width of the second portion of the chamber. The first portion of the chamber may have a depth that is substantially the same as the depth of the second portion of the chamber.

The first portion of the chamber and the second portion of the chamber may be located on opposing sides of the heating element to one another.

The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 100 cubic millimetres and 2000 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 200 cubic millimetres and 1800 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 300 cubic millimetres and 1600 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 350 cubic millimetres and 1400 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 400 cubic millimetres and 1200 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 450 cubic millimetres and 1000 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 500 cubic millimetres and 800 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 560 cubic millimetres and 700 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 580 cubic millimetres and 680 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 600 cubic millimetres and 660 cubic millimetres. The first portion of the chamber and the second portion of the chamber may have a combined internal volume of between 620 cubic millimetres and 640 cubic millimetres.

The first portion and the second portion may have a length of at least 8 millimetres. The first portion and the second portion may have a length of at least 8.5 millimetres. The first portion and the second portion may have a length of at least 9 millimetres. The first portion and the second portion may have a length of at least 9.5 millimetres. The first portion and the second portion may have a length of less than or equal to 11 millimetres. The first portion and the second portion may have a length of less than or equal to

10.5 millimetres. The first portion and the second portion may have a length of less than or equal to 10 millimetres.

The first portion and the second portion may have a length of between 8 millimetres and 11 millimetres. The first portion and the second portion may have a length of between 8.5 millimetres and 10.5 millimetres. The first portion and the second portion may have a length of between 9 millimetres and 10 millimetres.

The first portion and the second portion may have a width of at least 10 millimetres. The first portion and the second portion may have a width of at least 10.5 millimetres. The first portion and the second portion may have a width of at least 11 millimetres.

The first portion and the second portion may have a width of less than or equal to 13 millimetres. The first portion and the second portion may have a width of less than or equal to

12.5 millimetres. The first portion and the second portion may have a width of less than or equal to 12 millimetres. The first portion and the second portion may have a width of less than or equal to 11.5 millimetres.

The first portion and the second portion may have a width of between 10 millimetres and 13 millimetres. The first portion and the second portion may have a width of between 10.5 millimetres and 12.5 millimetres. The first portion and the second portion may have a width of between 11 millimetres and 12 millimetres.

The first portion and the second portion may have a depth of at least 5 millimetres. The first portion and the second portion may have a depth of at least 5.5 millimetres. The first portion and the second portion may have a depth of at least 5.7 millimetres.

The first portion and the second portion may have a depth of less than or equal to 7 millimetres. The first portion and the second portion may have a depth of less than or equal to 6.5 millimetres. The first portion and the second portion may have a depth of less than or equal to 6 millimetres. The first portion and the second portion may have a depth of less than or equal to 5.7 millimetres.

The first portion and the second portion may have a depth of between 5 millimetres and 6 millimetres.

The first portion of the chamber and the second portion of the chamber may be configured to accommodate an aerosol-generating substrate having a combined volume of between 530 cubic millimetres and 670 cubic millimetres. The first portion of the chamber and the second portion of the chamber may be configured to accommodate an aerosol-generating substrate having a combined volume of between 550 cubic millimetres and 650 cubic millimetres. The first portion of the chamber and the second portion of the chamber may be configured to accommodate an aerosol-generating substrate having a combined volume of between 570 cubic millimetres and 630 cubic millimetres. The first portion of the chamber and the second portion of the chamber may be configured to accommodate an aerosol-generating substrate having a combined volume of between 590 cubic millimetres and 610 cubic millimetres.

The first portion of the chamber may have a volume of between 250 cubic millimetres and 330 cubic millimetres. The first portion of the chamber may have a volume of between 270 cubic millimetres and 310 cubic millimetres.

The first portion may have a length of between 8 millimetres and 11 millimetres. The first portion may have a length of between 8.5 millimetres and 10.5 millimetres. The first portion may have a length of between 9 millimetres and 10 millimetres.

The first portion may have a width of between 10 millimetres and 13 millimetres. The first portion may have a width of between 10.5 millimetres and 12.5 millimetres. The first portion may have a width of between 1 1 millimetres and 12 millimetres.

The second portion of the chamber may have a volume of between 250 cubic millimetres and 330 cubic millimetres. The second portion of the chamber may have a volume of between 270 cubic millimetres and 310 cubic millimetres.

The second portion may have a length of between 8 millimetres and 1 1 millimetres. The second portion may have a length of between 8.5 millimetres and 10.5 millimetres. The second portion may have a length of between 9 millimetres and 10 millimetres.

The second portion may have a width of between 10 millimetres and 13 millimetres. The second portion may have a width of between 10.5 millimetres and 12.5 millimetres. The second portion may have a width of between 11 millimetres and 12 millimetres.

The heating element is a planar heating element. The heating element may be a resistive heating element.

The heating element may extend into the chamber.

The heating element may extend at least partially around the chamber.

For example, the heating element may extend around at least 50 percent of the chamber. The heating element may extend around at least 60 percent of the chamber. The heating element may extend around at least 70 percent of the chamber. The heating element may extend around at least 80 percent of the chamber. The heating element may extend around at least 90 percent of the chamber. The heating element may extend around at least 95 percent of the chamber. The heating element may extend around 100 percent of the chamber.

The heating element may extend around less than or equal to 95 percent of the chamber. The heating element may extend around less than or equal to 90 percent of the chamber. The heating element may extend around less than or equal to 80 percent of the chamber. The heating element may extend around less than or equal to 70 percent of the chamber. The heating element may extend fully around the chamber. The heating element may extend internally around the chamber. The heating element may extend around a periphery of the chamber.

The heating element may extend around an internal surface of the chamber. The heating element may be attached or mounted to the periphery of the chamber. The heating element may be attached or mounted to an inside surface of the chamber. The heating element may be a part of the housing. The heating element may be integrally formed with or in the housing.

The heating element may extend around at least 50 percent of the internal surface area of the chamber. The heating element may extend around at least 60 percent of the internal surface area of the chamber. The heating element may extend around at least 70 percent of the internal surface area of the chamber. The heating element may extend around at least 80 percent of the internal surface area of the chamber. The heating element may extend around at least 90 percent of the internal surface area of the chamber. The heating element may extend around at least 95 percent of the internal surface area of the chamber. The heating element may extend around 100 percent of the internal surface area of the chamber.

The heating element may extend around less than or equal to 95 percent of the internal surface area of the chamber. The heating element may extend around less than or equal to 90 percent of the internal surface area of the chamber. The heating element may extend around less than or equal to 80 percent of the internal surface area of the chamber. The heating element may extend around less than or equal to 70 percent of the internal surface area of the chamber.

The heating element may comprise one or more planar heating surfaces for heating an aerosol-generating substrate to form an aerosol.

The one or more planar heating surfaces may comprise a first planar heating surface for heating the first aerosol-generating substrate disposed within the first portion of the chamber to form an aerosol.

The one or more planar heating surfaces may comprise a second planar heating surface for heating the second aerosol-generating substrate disposed within the second portion of the chamber to form an aerosol.

At least one of the one or more heating surfaces may have a surface area of between 20 square millimetres and 200 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 20 square millimetres and 190 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 25 square millimetres and 180 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 30 square millimetres and 170 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 35 square millimetres and 160 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 40 square millimetres and 150 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 45 square millimetres and 140 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 50 square millimetres and 130 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 55 square millimetres and 120 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 60 square millimetres and 1 15 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 65 square millimetres and 110 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 70 square millimetres and 105 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 75 square millimetres and 100 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 80 square millimetres and 95 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 85 square millimetres and 90 square millimetres.

A ratio of the surface area of each of the one or more heating surfaces to the cross- sectional area of the chamber in the plane in which the heating element extends may be between 0.3 and 0.6. A ratio of the surface area of each of the one or more heating surfaces to the cross- sectional area of the chamber in the plane in which the heating element extends may be between 0.35 and 0.55. A ratio of the surface area of each of the one or more heating surfaces to the cross-sectional area of the chamber in the plane in which the heating element extends may be between 0.4 and 0.5.

The cross-sectional area of the heating element in the plane in which the heating element extends may be between 20 square millimetres and 200 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 25 square millimetres and 180 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 30 square millimetres and 160 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 35 square millimetres and 140 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 40 square millimetres and 120 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 45 square millimetres and 100 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 50 square millimetres and 95 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 60 square millimetres and 90 square millimetres. The cross- sectional area of the heating element in the plane in which the heating element extends may be between 65 square millimetres and 85 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 70 square millimetres and 80 square millimetres. The cross-sectional area of the heating element in the plane in which the heating element extends may be between 70 square millimetres and 75 square millimetres.

The cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 150 square millimetres and 250 square millimetres. The cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 150 square millimetres and 240 square millimetres. The cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 150 square millimetres and 230 square millimetres. The cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 160 square millimetres and 220 square millimetres. The cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 170 square millimetres and 210 square millimetres. The cross- sectional area of the chamber in the plane in which the planar heating element extends may be between 180 square millimetres and 200 square millimetres. The cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 160 square millimetres and 200 square millimetres.

A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 0.3 and 0.8.

A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 0.1 and 0.9. A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 0.15 and 0.8. A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 0.2 and 0.7. A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 0.25 and 0.6. A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends may be between 0.3 and 0.5.

The heating element may be fixedly attached to the downstream portion.

The heating element may extend from the downstream portion, into the chamber, and towards the upstream portion. The heating element may extend from the downstream portion, into the body, and towards the upstream portion.

The heating element may comprise one or more electrical connection portion. The one or more electrical connection portions may be electrically conductive. The one or more electrical connection portions may be spaced apart from one another. The one or more electrical connection portions may comprise a first electrical connection portion and a second electrical connection portion. The first electrical connection portion and the second electrical connection portion may be positioned on opposite sides of the outlet to one another. The first electrical connection portion and the second electrical connection portion may be configured to allow contact with an external power supply.

The one or more electrical connection portion may be disposed at the upstream portion.

The heating element may comprise an intermediate section extending between a downstream end section and an upstream end section. The downstream end section may be located at the downstream end of the cartridge. The upstream end section may be located at the upstream end of the cartridge.

The intermediate section may have a serpentine shape. The intermediate section may have a winding shape. The intermediate section may have a spiral shape. The intermediate section may have a flower-like shape.

The intermediate section may comprise a plurality of segments. The intermediate section may comprise at least eight segments. The intermediate section may comprise less than or equal to sixteen segments. The plurality of segments may be parallel to one another. The plurality of segments may extend along the longitudinal axis of the cartridge.

Each of the plurality of segments may have a width of at least 0.26 millimetres. Each of the plurality of segments may have a width of at least 0.27 millimetres. Each of the plurality of segments may have a width of at least 0.28 millimetres. Each of the plurality of segments may have a width of at least 0.29 millimetres. Each of the plurality of segments may have a width of at least 0.3 millimetres.

Each of the plurality of segments may have a width of less than or equal to 0.34 millimetres. Each of the plurality of segments may have a width of less than or equal to 0.33 millimetres. Each of the plurality of segments may have a width of less than or equal to 0.32 millimetres. Each of the plurality of segments may have a width of less than or equal to 0.31 millimetres. Each of the plurality of segments may have a width of less than or equal to 0.3 millimetres.

Each of the plurality of segments may have a width of less between 0.26 millimetres and 0.34 millimetres. Each of the plurality of segments may have a width of less between 0.27 millimetres and 0.33 millimetres. Each of the plurality of segments may have a width of less between 0.28 millimetres and 0.32 millimetres. Each of the plurality of segments may have a width of less between 0.29 millimetres and 0.31 millimetres.

The plurality of segments may be separated from one another by a gap.

The gap may have a width of between 0.28 millimetres and 0.36 millimetres. The gap may have a width of between 0.29 millimetres and 0.35 millimetres. The gap may have a width of between 0.3 millimetres and 0.34 millimetres. The gap may have a width of between 0.31 millimetres and 0.33 millimetres.

The heating element may be formed from an iron-based alloy. The heating element may be formed from a nickel alloy. The heating element may be formed from a ceramic. The heating element may be formed from stainless steel. The heating element may be formed from SS316L stainless steel iron aluminides. The heating element may be formed from nichrome. The heating element may be formed from a ceramic coated metal.

The heating element may have a length of between 13 millimetres and 20 millimetres. The heating element may have a length of between 13.5 millimetres and 19.5 millimetres. The heating element may have a length of between 14 millimetres and 19 millimetres. The heating element may have a length of between 14.5 millimetres and 18.5 millimetres. The heating element may have a length of between 15 millimetres and 18 millimetres. The heating element may have a length of between 15.5 millimetres and 17.5 millimetres. The heating element may have a length of between 16 millimetres and 17 millimetres.

The heating element may have a width of between 8 millimetres and 12 millimetres. The heating element may have a width of between 8.5 millimetres and 1 1.5 millimetres. The heating element may have a width of between 9 millimetres and 1 1 millimetres. The heating element may have a width of between 9.5 millimetres and 10.5 millimetres.

The heating element may have a thickness of between 0.1 millimetres and 0.3 millimetres.

At least one of the one or more heating surfaces may have a surface area of between 70 square millimetres and 110 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 75 square millimetres and 105 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 80 square millimetres and 100 square millimetres. At least one of the one or more heating surfaces may have a surface area of between 85 square millimetres and 95 square millimetres.

The surface area of the first heating surface may be substantially the same as the surface area of the second heating surface.

The inlet may extend along the width of the housing. The outlet may extend along the width of the housing. The heating element may be aligned with the at least one of the inlet and the outlet.

There is also provided an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating device. The aerosol-generating system may comprise a cartridge. The cartridge may comprise a housing having an inlet and an outlet. The cartridge may comprise a chamber between the inlet and the outlet. The cartridge may comprise a heating element for heating an aerosol forming substrate to form an aerosol. The heating element may extend into the chamber. The chamber may comprise a first portion on a first side of the heating element and a second portion on a second side of the heating element. The cartridge may comprise an aerosol generating substrate disposed within at least one of the first portion and the second portion. The first portion and the second portion may have a combined internal volume of at least 500 cubic millimetres.

There is also provided an aerosol-generating system comprising an aerosol-generating device and a cartridge, the cartridge comprising: a housing having an inlet and an outlet, and a chamber between the inlet and the outlet; a heating element for heating an aerosol forming substrate to form an aerosol, the heating element extending into the chamber; the chamber comprising a first portion on a first side of the heating element and a second portion on a second side of the heating element; and an aerosol generating substrate disposed within at least one of the first portion and the second portion, wherein the first portion and the second portion have a combined internal volume of at least 500 cubic millimetres.

The aerosol-generating device may comprise a device body.

The aerosol-generating device may comprise a device cavity for receiving the cartridge.

The aerosol-generating device may comprise a lid.

The aerosol-generating device may comprise a power source. The power source may be a battery.

The aerosol-generating device may comprise a controller.

Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

EX1 . A cartridge for an aerosol-generating device, the cartridge comprising: a housing having an inlet and an outlet and an aerosol-generating substrate.

EX2. A cartridge according to example EX1 , comprising a chamber between the inlet and the outlet.

EX3. A cartridge according to example EX2, comprising a heating element for heating the aerosol forming substrate to form an aerosol.

EX4. A cartridge according example EX3, wherein the heating element extends into the chamber.

EX5. A cartridge according to example EX3 or EX4, wherein the chamber comprises a first portion on a first side of the heating element and a second portion on a second side of the heating element.

EX6. A cartridge according to example EX5, wherein the aerosol generating substrate ia disposed within at least one of the first portion and the second portion.

EX7. A cartridge according to any of the preceding examples, wherein the housing comprises a body extending between an upstream portion and a downstream portion.

EX8. A cartridge according to example EX7, wherein the upstream portion comprises the inlet. EX9. A cartridge according to example EX7 or EX8, wherein the downstream portion comprises the outlet.

EX10. A cartridge according to any of examples EX7 to EX9, wherein, at an axial cross-section, the body has an internal area of at least 40 square millimetres.

EX1 1 . A cartridge according to any of examples EX7 to EX10, wherein, at an axial cross-section, the body has an internal area of less than or equal to 80 square millimetres.

EX12. A cartridge according to any of examples EX7 to EX1 1 , wherein, at an axial cross-section, the body has an internal area of between 40 square millimetres and 80 square millimetres.

EX13. A cartridge according to example EX12, wherein, at an axial cross-section, the body has an internal area of between 50 square millimetres and 70 square millimetres.

EX14. A cartridge according to any of examples EX7 to EX13, wherein, at an axial cross-section, the body has an external perimeter of at least 30 millimetres.

EX15. A cartridge according to any of examples EX7 to EX14, wherein, at an axial cross-section, the body has an external perimeter of less than or equal to 40 millimetres.

EX16. A cartridge according to any of examples EX7 to EX15, wherein, at an axial cross-section, the body has an external perimeter of between 30 millimetres and 40 millimetres.

EX17. A cartridge according to any of examples EX7 to EX16, wherein a ratio of the external perimeter to the internal area is at least 0.38.

EX18. A cartridge according to example EX17, wherein a ratio of the external perimeter to the internal area is at least 0.45.

EX19. A cartridge according to any of examples EX7 to EX18, wherein a ratio of the external perimeter to the internal area is less than or equal to 0.5.

EX20. A cartridge according to any of examples EX7 to EX19, wherein a ratio of the external perimeter to the internal area is between 0.38 and 0.5.

EX21. A cartridge according to example EX4, wherein the cross-sectional area of the heating element in the plane in which the heating element extends is at least 60 square millimetres.

EX22. A cartridge according to example EX4 or EX21 , wherein the cross-sectional area of the heating element in the plane in which the heating element extends is less than or equal to 90 square millimetres.

EX23. A cartridge according to any of examples EX4, EX21 or EX22, wherein the cross-sectional area of the heating element in the plane in which the heating element extends is between 60 square millimetres and 90 square millimetres.

EX24. A cartridge according to example EX23, wherein the cross-sectional area of the heating element in the plane in which the heating element extends is between 70 square millimetres and 80 square millimetres. EX25. A cartridge according to any of examples EX4 or EX21 to EX24, wherein the cross- sectional area of the chamber in the plane in which the planar heating element extends is at least 150 square millimetres.

EX26. A cartridge according to any of examples EX4 or EX21 to EX25, wherein the cross- sectional area of the chamber in the plane in which the planar heating element extends is less than or equal to 250 square millimetres.

EX27. A cartridge according to any of examples EX4 or EX21 to EX26, wherein the cross- sectional area of the chamber in the plane in which the planar heating element extends is between 150 square millimetres and 250 square millimetres.

EX28. A cartridge according to any of examples EX4 or EX21 to EX27, wherein the cross- sectional area of the chamber in the plane in which the planar heating element extends is between 160 square millimetres and 200 square millimetres.

EX29. A cartridge according to any of examples EX4 or EX21 to EX28, wherein a ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends is at least 30 percent.

EX30. A cartridge according to any of examples EX4 or EX21 to EX29, wherein a ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends is less than or equal to 80 percent.

EX31. A cartridge according to any of examples EX4 or EX21 to EX30, wherein a ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends is between 30 percent and 80 percent.

EX32. A cartridge according to example EX31 , wherein a ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber in the plane in which the planar heating element extends is between 30 percent and 50 percent.

EX33. A cartridge according to any of examples EX4 or EX21 to EX32, wherein the heating element is a planar heating element.

EX34. A cartridge according to example EX33, wherein the planar heating element comprises one or more planar heating surfaces for heating the aerosol-generating substrate to form an aerosol.

EX35. A cartridge according to example EX33 or example EX34, wherein the planar heating element comprises two planar heating surfaces for heating the aerosol-generating substrate to form an aerosol. EX36. A cartridge according to example EX34 or example EX35, wherein each of the one or more planar heating surfaces has a surface area of at least 55 square millimetres.

EX37. A cartridge according to any of examples EX34 to EX36, wherein each of the one or more planar heating surfaces has a surface area of less than or equal to 120 square millimetres.

EX38. A cartridge according to any of examples EX34 to EX37, wherein each of the one or more planar heating surfaces has a surface area of between 55 square millimetres and 120 square millimetres.

EX39. A cartridge according to any of examples EX34 to EX38, wherein a ratio of the surface area of each of the one or more planar heating surfaces to the cross-sectional area of the chamber in the plane in which the planar heating element extends is at least 30 percent.

EX40. A cartridge according to any of examples EX34 to EX39, wherein a ratio of the surface area of each of the one or more planar heating surfaces to the cross-sectional area of the chamber in the plane in which the planar heating element extends is less than or equal to 60 percent.

EX41 . A cartridge according to any of examples EX34 to EX40, wherein a ratio of the surface area of each of the one or more planar heating surfaces to the cross-sectional area of the chamber in the plane in which the planar heating element extends is between 30 percent and 60 percent. EX42 A cartridge according to example EX5, wherein the first portion and the second portion have a combined internal volume of at least 400 cubic millimetres.

EX43. A cartridge according to example EX5 or example EX42, wherein the first portion and the second portion have a combined internal volume of at least 500 cubic millimetres.

EX44. A cartridge according to any of examples EX5, EX42 or EX43, wherein the first portion and the second portion have a combined internal volume of less than or equal to 800 cubic millimetres.

EX45. A cartridge according to any of examples EX5, or EX42 to EX44, wherein the first portion and the second portion have a combined internal volume of less than or equal to 700 cubic millimetres.

EX46. A cartridge according to any of examples EX5, or EX42 to EX45, wherein the first portion and the second portion have a combined internal volume of between 500 cubic millimetres and 700 cubic millimetres.

EX47. A cartridge according to any of examples EX5, or EX42 to EX46, wherein the aerosolgenerating substrate comprises a first aerosol-generating substrate disposed in the first portion and a second aerosol-generating substrate disposed in the second portion.

EX48. A cartridge according to any preceding example, wherein the housing has an external volume of at least 1300 cubic millimetres.

EX49. A cartridge according to any preceding example, wherein the housing has an external volume of less than or equal to 1500 cubic millimetres. EX50. A cartridge according to any preceding example, wherein the housing has an external volume of between 1300 cubic millimetres and 1500 cubic millimetres.

EX51 . A cartridge according to example EX5, wherein the internal volume of the first portion is substantially the same as the internal volume of the second portion.

EX52. A cartridge according to example EX5 or example EX51 , wherein the first portion is substantially the same as the chamber second portion in terms of at least one of: shape; size; thickness; width; length; orientation.

EX53. A cartridge according to any preceding example, wherein the housing is a rigid housing.

EX54. A cartridge according to example EX7, wherein the body has an external length of between 16 millimetres and 18 millimetres.

EX55. A cartridge according to example EX7 or example EX54, wherein the body has an external width of between 1 1.5 millimetres and 13 millimetres.

EX56. A cartridge according to any of examples EX7, EX54 or EX55, wherein the body has an external depth of between 5 millimetres and 6.5 millimetres.

EX57. A cartridge according to any preceding example, wherein the inlet comprises a plurality of inlet apertures.

EX58. A cartridge according to any preceding example, wherein the outlet comprises a plurality of outlet apertures.

EX59. A cartridge according to any preceding example, comprising an air flow path extending between the inlet and the outlet.

EX60. A cartridge according to example EX3 or example EX4, wherein heating element comprises an intermediate section extending between a downstream end section and an upstream end section.

EX61. A cartridge according to example EX60, wherein the intermediate section has: a serpentine shape; a winding shape; a spiral shape; or a flower-like shape.

EX62. A cartridge according to example EX60 or example EX61 , wherein the intermediate section comprises a plurality of segments.

EX63. A cartridge according to example EX62, wherein the plurality of segments are parallel to one another.

EX64. A cartridge according to example EX63, wherein the plurality of segments extend along the longitudinal axis of the cartridge.

EX65. A cartridge according to any preceding example, wherein the cartridge comprises one or more solid aerosol-generating substrates.

EX66. A cartridge according to example EX65, wherein the one or more solid aerosol-generating substrate are provided within a chamber defined between the inlet and the outlet and wherein the density of the aerosol-generating substrate within the chamber is at least 0.1 milligrams per cubic millimetre of the chamber. EX67. A cartridge according to example EX66, wherein the density of the aerosol-generating substrate within the chamber is at least 0.3 milligrams per cubic millimetre of the chamber.

EX68. A cartridge according to example EX66 or EX67, wherein the density of the aerosolgenerating substrate within the chamber is less than 2 milligrams per cubic millimetre of the chamber.

EX69. A cartridge according to EX66 or EX67, wherein the density of the aerosol-generating substrate within the chamber is less than 1 milligram per cubic millimetre of the chamber.

EX70. A cartridge according to any preceding example, wherein the cartridge comprises a planar heating element comprising one or more planar heating surfaces and wherein the aerosolgenerating substrate is configured to be in direct contact with the one or more planar heating surfaces over a total surface area that corresponds to at least 35 percent of the total cross- sectional area of the chamber in the plane in which the planar heating element extends.

EX71. A cartridge according to example, wherein the aerosol-generating substrate is in direct contact with the planar heating surfaces over a total area of at least 40 square millimetres.

EX72. A cartridge according to any preceding example EX71 , wherein the aerosol-generating substrate is in direct contact with the planar heating surfaces over a total area of up to 120 square millimetres.

EX73. A cartridge according to any preceding example, wherein the aerosol-generating substrate is provided within a chamber defined between the inlet and the outlet and wherein the percentage fill of the chamber by the aerosol-generating substrate is at least 50 percent.

EX74. A cartridge according to any preceding example, wherein the aerosol-generating substrate comprises an aerosol former.

EX75. A cartridge according to example EX74, wherein the aerosol-generating substrate comprises at least 5 percent by weight of aerosol former on a dry weight basis.

EX76. A cartridge according to example EX75, wherein the aerosol-generating substrate comprises up to 30 percent by weight of aerosol former on a dry weight basis.

EX77. A cartridge according to example EX74, wherein the aerosol-generating substrate comprises at least 40 percent by weight of aerosol former on a dry weight basis.

EX78. A cartridge according to example EX77, wherein the aerosol-generating substrate comprises up to 80 percent by weight of aerosol former on a dry weight basis.

EX79. A cartridge according to any preceding example, wherein the aerosol-generating substrate comprises extrinsic nicotine.

EX80. A cartridge according to any preceding example, wherein the aerosol-generating substrate comprises tobacco.

EX81 . A cartridge according to any of examples EX1 to EX79 , wherein the aerosol-generating substrate is substantially free from tobacco. EX82. A cartridge according to any preceding example, wherein the aerosol-generating substrate comprises at least 0.5 percent by weight of nicotine on a dry weight basis.

EX83. A cartridge according to any preceding example, wherein the aerosol-generating substrate comprises up to 10 percent by weight of nicotine on a dry weight basis.

EX84. A cartridge according to any preceding example, wherein the aerosol-generating substrate is in the form of one or more sheets of solid aerosol-generating substrate.

EX85. A cartridge according to example EX84, wherein the aerosol-generating substrate is provided within a chamber defined between the inlet and the outlet and wherein the density of the aerosol-generating substrate is between 0.3 milligrams per cubic millimetre and 2 milligrams per cubic millimetre of the chamber.

EX86. A cartridge according to example EX84 or EX85, wherein each of the one or more sheets has an average thickness of less than 500 microns.

EX87. A cartridge according to example EX84 or EX85, wherein each of the one or more sheets has an average thickness of at least 1 millimetre.

EX88. A cartridge according to any of examples EX84 to EX87, wherein the one or more sheets of aerosol-generating substrate are gathered.

EX89. A cartridge according to any of examples EX84 to EX88 , wherein the one or more sheets of aerosol-generating substrate are crimped.

EX90. A cartridge according to any of examples EX84 to EX89, wherein the aerosol-generating substrate is provided within a chamber defined between the inlet and the outlet and wherein the chamber of the cartridge contains at least 250 milligrams of the one or more sheets of solid aerosol-generating substrate.

EX91 . A cartridge according to any of examples EX84 to EX90 , wherein the one or more sheets of aerosol-generating substrate comprise one or more sheets of homogenised plant material.

EX92. A cartridge according to any of examples EX84 to EX91 , wherein the one or more sheets of aerosol-generating substrate comprise one or more sheets of homogenised tobacco material. EX93. A cartridge according to any of examples EX84 to EX92 , wherein the one or more sheets of aerosol-generating substrate comprise one or more sheets of aerosol-generating film comprising a cellulosic based film forming agent, nicotine and aerosol former.

EX94. A cartridge according to any of examples EX84 to EX93 , wherein the one or more sheets of aerosol-generating substrate comprise one or more sheets comprising a gel composition comprising nicotine, at least one gelling agent and an aerosol former.

EX95. A cartridge according to any of examples EX1 to EX83, wherein the aerosol-generating substrate is provided within a chamber defined between the inlet and the outlet and wherein the aerosol-generating substrate is in the form of a shredded aerosol-generating substrate. EX96. A cartridge according to example EX95, wherein the density of the shredded aerosolgenerating substrate is between 0.1 milligrams per cubic millimetre and 1 milligram per cubic millimetre of the chamber.

EX97. A cartridge according to any of examples EX95 to EX96, wherein the chamber of the cartridge contains at least 100 milligrams of the shredded aerosol-generating substrate.

EX98. A cartridge according to any of examples EX95 to EX97, wherein the shredded aerosolgenerating substrate has a cut width of at least 0.3 millimetres.

EX99. A cartridge according to any of examples EX95 to EX98, wherein the shredded aerosolgenerating substrate has a cut width of less than 2 millimetres.

EX100. A cartridge according to any of examples EX95 to EX99, wherein the shredded aerosolgenerating substrate comprises cut filler.

EX101 . A cartridge according to any of examples EX95 to EX100, wherein the shredded aerosolgenerating substrate comprises homogenised plant material.

EX102. A cartridge according to any of examples EX95 to EX101 , wherein the shredded aerosolgenerating substrate comprises an aerosol-generating film comprising a cellulosic based film forming agent, nicotine and aerosol former.

EX103. A cartridge according to any of examples EX95 to EX102, wherein the shredded aerosolgenerating substrate comprises a gel composition comprising nicotine, at least one gelling agent and an aerosol former.

EX104. A cartridge according to any of examples EX1 to EX83, wherein the aerosol-generating substrate comprises a plurality of particles.

EX105. A cartridge according to example EX104, wherein the aerosol-generating substrate comprises at least one of tobacco or nicotine.

EX106. A cartridge according to example EX104, wherein the aerosol-generating substrate is provided within a chamber defined between the inlet and the outlet and wherein the density of the aerosol-generating substrate is between 0.3 milligrams per cubic millimetre and 2 milligrams per cubic millimetre of the chamber.

EX107. A cartridge according to any of examples EX104 to EX106, wherein the plurality of particles are provided within a permeable pouch.

EX108. A cartridge according to example EX107, wherein the pouch has an external volume of at least 180 cubic millimetres.

EX109. A cartridge according to any of examples EX104 to EX106, wherein the plurality of particles are pressed into one or more tablets.

EX1 10. A cartridge according to any of examples EX104 to EX106, wherein the plurality of particles are in the form of loose particles.

EX1 1 1. A cartridge according to any of examples EX104 to EX110, wherein the aerosolgenerating substrate is in the form of a powder. EX1 12. A cartridge according to example EX1 11 , wherein the powder has a D50 size of between 50 micrometres and 80 micrometres.

EX1 13. A cartridge according to example EX11 1 or EX112, wherein the powder has a D95 size of between 80 micrometres and 130 micrometres.

EX1 14. A cartridge according to any of examples EX104 to EX113, wherein the aerosolgenerating substrate is in the form of ground tobacco.

EX1 15. A cartridge according to any of examples EX104 to EX113, wherein the aerosolgenerating substrate comprises a plurality of particles comprising a gel composition comprising nicotine, at least one gelling agent and an aerosol former.

In the following, the invention will be further described with reference to the drawings of the accompanying Figures, in which:

Figure 1 is a schematic illustration of a cartridge in accordance with an example of the present disclosure;

Figure 2 is a cross-sectional illustration of the cartridge of Figure 1 , without an aerosolgenerating substrate;

Figure 3 is a cross-sectional illustration of the cartridge of Figure 1 , with an aerosolgenerating substrate;

Figure 4 is a cross-sectional illustration of the cartridge of Figure 1 , in a view perpendicular to the cross-sections of figures 2 and 3; and

Figure 5 is a cross-sectional illustration of a system in accordance with an example of the present disclosure.

Referring to figure 1 , there is shown a schematic illustration of a cartridge 10 in accordance with an example of the present disclosure. The cartridge 10 is configured for use with an aerosolgenerating device 600. As best seen in figures 2 and 3, the cartridge 10 comprises: a housing 100; a planar heating element 200; and an aerosol-generating substrate 300.

The housing 100 of the cartridge 10 is configured to protect, contain or support components of the cartridge 10. The housing 100 of the cartridge is configured to contain the aerosolgenerating substrate 300. The housing 100 is configured to hold the aerosol-generating substrate 300 in the chamber 400 in contact with or proximate to the heating element 200. The housing 100 is a rigid housing. The housing 100 has an internal volume of between 1300 cubic millimetres and 1500 cubic millimetres.

The housing 100 has an inlet 1 10, an outlet 120, and a chamber 400. The housing 100 has a distal end 101 and a proximal end 102. The housing 100 comprises an air flow path extending between the inlet 1 10 and the outlet 120. The housing 100 defines the inlet 110 and the outlet 120. The housing 100 is configured such that in use, air can flow from the inlet 110, through the chamber 400, towards and out through the outlet 120. The inlet 1 10 is an air inlet. The inlet 1 10 is disposed at the distal end 101 . As best seen in figure 4, the inlet 1 10 comprises a plurality of inlet apertures 11 1. The inlet apertures 11 1 are equally spaced from one another. The inlet apertures 1 11 have substantially the same shape, size and orientation as one another.

The outlet 120 is an aerosol outlet. The outlet 120 is disposed at the proximal end 102. The outlet 120 comprises a plurality of outlet apertures 121. The outlet apertures 121 are equally spaced from one another. The outlet apertures 121 have substantially the same shape, size and orientation as one another.

The housing 100 has an upstream portion 130. The housing 100 has a downstream portion 140. The housing 100 has a body 150.

The upstream portion 130 is located at the upstream end 101 of the cartridge 10. The upstream portion 130 is fixed to the body 150. The upstream portion 130 is fixed to the body 150 by an interference fit. The upstream portion 130 comprises the inlet 110. The inlet 1 10 is within the body 150. The upstream portion 130 is an upstream end cap. The upstream portion 130 extends into the body 150. The upstream portion 130 has a length (i.e. a dimension in the third direction 3) of between 3 millimetres and 4.5 millimetres. The upstream portion 130 may comprise a transparent or translucent material. The upstream portion 130 may comprise plastic, such as high temperature plastic.

The upstream portion 130 has an upstream portion base 135 and an upstream portion insert 136. The upstream portion base 135 is substantially outside of the body 150. The upstream portion base 135 has the same depth as the body 150. The upstream portion base 135 has the same width as the body 150.

The upstream portion insert 136 is attached to the upstream portion base 135. The upstream portion insert 136 is formed as an integral piece with the upstream portion base 135. The upstream portion insert 136 extends from the upstream portion base 135 into the body 150. The upstream portion insert 136 is substantially within the body 150. The upstream portion insert 136 defines the inlet 1 10. The upstream portion insert 136 has an outer wall which is substantially aligned with an inner wall of the body 150. The upstream portion insert 136 is located such that the upstream portion base 135 abuts an end of the body 150. The upstream portion insert 136 is fixed to the body 150 by an interference fit.

The downstream portion 140 is located at a downstream end 102 of the cartridge 10. The downstream portion 140 is fixed to the body 150. The downstream portion 140 is fixed to the body 150 by an interference fit. The downstream portion 140 comprises the outlet 120. The downstream portion 140 is a downstream end cap. The downstream portion 140 extends into the body 150. The downstream portion 140 is located downstream of the upstream portion 130. The downstream portion 140 has a length of between 2.5 millimetres and 4 millimetres. The downstream portion 140 may comprise a transparent or translucent material. The downstream portion 140 may comprise plastic, such as high temperature plastic.

The downstream portion 140 comprises a downstream portion base 145 and a downstream portion insert 146. The downstream portion base 145 defines the outlet 120. The outlet 120 is aligned with a downstream end of the body 150. The downstream portion base 145 is planar. The downstream portion base 145 is substantially outside of the body 150. The downstream portion base 145 has the same depth as the body 150. The downstream portion base 145 has the same width as the body 150.

The downstream portion insert 146 is attached to the downstream portion base 145. The downstream portion insert 146 is formed as an integral piece with the downstream portion base 145. The downstream portion insert 146 extends from the downstream portion base 145 into the body 150. The downstream portion insert 146 is substantially hollow. The downstream portion insert 146 is tubular. The downstream portion insert 146 is substantially within the body 150. The downstream portion insert 146 has an outer wall which is substantially aligned with an inner wall of the body 150. The downstream portion insert 146 is located such that the downstream portion base 145 abuts an end of the body 150.

The chamber 400 extends between the inlet 1 10 and the outlet 120. The chamber 400 comprises a downstream cavity 440 defined by the downstream portion 140. The downstream cavity 440 is entirely within the downstream portion insert 146. The downstream cavity 440 has an internal volume of between 70 cubic millimetres and 90 cubic millimetres. The heating element 200 extends only partly through the downstream cavity 440. The downstream cavity 440 comprises a first portion 441 on the first side of a plane defined by the planar heating element 200 and a second portion 442 on the second side of a plane defined by the planar heating element 200. Given that the heating element 200 extends only partly through the downstream cavity 440, the first portion 441 is only partly separated from the second portion 442 by the heating element 200. The first portion 441 of the downstream cavity 440 and the second portion 442 of the downstream cavity 440 have a combined internal volume of between 70 cubic millimetres and 90 cubic millimetres.

The body 150 extends between the upstream portion 130 and the downstream portion 140. The body 150 defines the chamber 400 between the downstream portion 140 and the upstream portion 130. The body 150 has an external length of between 16 millimetres and 18 millimetres. The body 150 has an external width of between 1 1.5 millimetres and 13 millimetres. The body 150 has an external depth of between 5 millimetres and 6.5 millimetres. The body 150 has a surface area of between 540 square millimetres and 565 square millimetres. The body 150 has a wall having a wall thickness of 0.5 millimetres. The body 150 has a substantially constant wall thickness along its length. The body 150 has a substantially constant wall thickness along its width. The body 150 has a substantially constant wall thickness along its depth. The body 150 is substantially tubular. The body 150 has a substantially rectangular longitudinal cross-section. The body 150 may comprise at least one of: a metal; an alloy; plastic; high-temperature plastic; plant material.

The chamber 400 is configured to store the aerosol-generating substrate 300. The chamber 400 is located between the inlet 1 10 and the outlet 120. The chamber 400 is defined by the housing 100. The only openings to the chamber 400 are the inlet 110 and the outlet 120.

The chamber 400 comprises a first portion 410 and a second portion 420. The first portion 410 is on a first side of the heating element 200 and the second portion 420 is on a second side of the heating element 200. The first portion 410 and the second portion 420 have a combined internal volume of at least 500 cubic millimetres. The internal volume of the first portion 410 is substantially the same as the internal volume of the second portion 420. The first portion 410 is substantially the same as the second portion 420 in terms of at least one of: shape; size; depth; width; length; orientation. The first and second portions 410, 420 are configured such that in use, air can flow from the inlet 1 10, through the aerosol-generating substrate 310, 320 in both portions of the chamber 410, 420 in parallel, towards and out through the outlet 120. Specifically, air flow may diverge after entering the inlet 1 10 so that it can pass through both of the first and second portions 410, 420, then converge to pass through the outlet 120.

The planar heating element 200 is configured to heat the aerosol forming substrate to form an aerosol. The heating element 200 is a resistive heating element, which is configured to generate heat upon application of a voltage across the heating element 200. The heating element 200 extends into the chamber 400. The heating element 200 extends into the chamber 400 from the upstream end towards the downstream end so as to divide the chamber 400 into a first portion 410 and a second portion 420. The heating element 200 is arranged so as to substantially separate the first aerosol-generating substrate 310 and the second aerosol-generating substrate 320 from one another.

The heating element 200 is fixedly attached to the housing 100. The heating element 200 is fixedly attached to the distal end 101 of the housing 100. The heating element 200 is fixedly attached to the upstream portion 130. The heating element 200 extends from the upstream portion 130, through the chamber 400, towards the downstream portion 140. The heating element 200 extends from the distal end 101 of the housing 100. The heating element 200 is embedded within a first upstream section 131 and a second upstream section 132 of the housing 100. The first upstream section 131 and the second upstream section 132 extend from the upstream portion 130, so as to clamp or fix the heating element 200 to the upstream portion 130. The heating element 200 extends through the aerosol-generating substrate 300. The heating element 200 is in contact with the aerosol-generating substrate 300.

The heating element 200 has a serpentine shape. The heating element 200 includes a plurality of parallel segments extending along the chamber 400. The heating element 200 is a self-supporting track which extends through the chamber 400. The heating element 200 is substantially or entirely planar. The heating element 200 extends across at least 20%, preferably at least 40% of the length of the chamber 400. The planar heating element 200 is oriented so that a plane of the heating element 200 is aligned with the cartridge width. The planar heating element 200 is oriented so that a plane of the heating element 200 is parallel to the cartridge width direction 1.

The heating element 200 comprises a first electrical connection portion 211 and a second electrical connection portion 212. The electrical connection portions 211 , 212 are connected to the upstream portion 130. The electrical connection portions 211 , 212 are configured for electrical connection to a power source. The electrical connection portions 21 1 , 212 are spaced apart from each other. The electrical connection portions 211 , 212 are spaced apart from each other in a width direction of the cartridge 10. The electrical connection portions 211 , 212 are on opposite sides of the chamber 400 to each other. The electrical connection portions 21 1 , 212 are towards opposite sides of the upstream portion 130. The electrical connection portions 211 , 212 are both fixedly attached to the first upstream section 131 and the second upstream section 132.

The heating element 200 comprises a serpentine portion 213. The serpentine portion 213 electrically connects the first electrical connection portion 21 1 to the second electrical connection portion 212. The serpentine portion 213 is shaped so as to have a greater length close to a central longitudinal axis of the cartridge 10 than its length close to the first or second electrical connection portions 21 1 , 212. The serpentine portion 213 is planar. The serpentine portion 213 has a series of flat track portions which together define a plane.

The heating element 200 comprises at least one of: an iron-based alloy; a nickel alloy; a ceramic.

Each electrical connection portion 21 1 , 212 of the heating element 200 is electrically connected to a cartridge electrical contact 221 , 222, as seen in figure 5. The cartridge electrical contacts 21 1 , 212 are provided at the downstream end 101 of the cartridge 10, at a surface of the housing 100.

As shown in figure 3, the aerosol-generating substrate 300 comprises a first aerosolgenerating substrate 310 and a second aerosol-generating substrate 320. The aerosol-generating substrate 300 is disposed within the first and second portions of the chamber 410, 420. The first aerosol-generating substrate 310 is disposed within a first portion 410 of the chamber 400. The second aerosol-generating substrate 320 is disposed within a second portion 420 of the chamber 400.

The aerosol-generating substrate 300 comprises loose shredded tobacco material in the form of tobacco cut filler soaked with an aerosol former. Optionally, a flavourant may additionally be applied to the tobacco cut filler. The tobacco cut filler has a cut width of 0.8 millimetres. The bulk density of the solid aerosol-generating substrate 300 within the chamber is approximately 0.4 milligrams per cubic millimetre of the chamber. The first aerosol-generating substrate 310 and the second aerosol-generating substrate 320 comprise shredded tobacco material having the same properties. However, in alternative embodiments of the invention, the first aerosolgenerating substrate 310 and second aerosol-generating substrate 320 may be formed of shredded tobacco materials having a different composition to each other. For example, the first aerosol-generating substrate 310 may comprise shredded tobacco material in the form of tobacco cut filler to which a first flavourant has been applied and the second aerosol-generating substrate may comprise shredded tobacco material in the form of tobacco cut filler to which a second flavourant has been applied.

As best seen in figure 1 , the housing has an external width 181 in a first direction 1. The housing has an external depth 182 in a second direction 2. The housing has an external length 183 in a third direction 3. The third direction 3 is a direction from the distal end 101 to the proximal end 102. The first, second and third directions 1 , 2, 3 are perpendicular to each other. The housing external length 183 is greater than the housing external width 181. The housing external width 181 is greater than the housing external depth 182.

The housing has an internal width 171 in the first direction 1. The housing has an internal depth 172 in the second direction 2. The housing has a housing body internal length 173 in the third direction 3. The housing body internal length 173 is greater than the housing internal width 171. The housing internal width 171 is greater than the housing internal depth 172.

The combined internal volume is the space within the cartridge 10 which is configured to receive aerosol-generating substrate 300. The combined internal volume of the chamber 400 may be partly or wholly filled with aerosol-generating substrate 300. The combined internal volume of the chamber 400 may be wholly or partly divided into two sections by the heating element 200.

The body 150 has dimensions at an axial cross-section of: an internal area of between 10 and 300 square millimetres; and an external perimeter of at least 30 millimetres. The ratio between the external perimeter and the internal area is at least 0.5.

The cartridge 10 depicted in the figures has a substantially constant cross-section along its length 183.

A cross-sectional area of the heating element in the plane in which the heating element extends is between 60 square millimetres and 90 square millimetres.

The cross-sectional area of the chamber 400 in the plane in which the planar heating element 200 extends is between 150 square millimetres and 250 square millimetres.

A ratio of the cross-sectional area of the heating element in the plane in which the heating element extends to the cross-sectional area of the chamber 400 in the plane in which the planar heating element extends is at least 0.3.

The cross-sectional area of the chamber 400 in the plane in which the planar heating element 200 extends is approximately the housing internal length multiplied by the housing internal width 171. The housing internal length is the housing body internal length 173 minus the length of any upstream or downstream portion which extends into the housing body 150 to occupy space in the plane of the heating element 200. With reference to figure 2, the upstream portion 130 occupies more space in the plane of the heating element 200 within the housing body 150 than the downstream portion 140.

The device 600 comprises a body 610; a device cavity and a lid 61 1 . As shown in figure 5, the cartridge 10 is configured to be received in the device cavity of the body 610 and the lid 61 1 of the device 600. The lid 61 1 is configured to move between an open position and a closed position. When the lid 611 is in the open position, the cartridge 10 can be inserted into or removed from the device cavity. When the lid 61 1 is in the closed position, the cartridge 10 is secured within the device 600. When the lid 611 is in the closed position, the cartridge 10 is contained within and surrounded by the lid 61 1 and the body 610 of the device 600, within the device cavity.

The device 600 comprises an inlet 608, an outlet 609, a power source 630, a controller 640, electrical contacts 621 , 622 and a mouthpiece 612. The body 610 comprises the inlet 608, the power source 630, the controller 640, and electrical contacts 621 , 622. The lid 61 1 comprises the mouthpiece 612 and the outlet 609.

The inlet 608 is disposed in the device body 610. The inlet 608 is disposed at a distal end of the device 600. The inlet 608 is an air inlet. The outlet 609 is disposed in the mouthpiece 612. The outlet 609 is disposed at a proximal end of the device 600. The outlet 609 is an aerosol outlet.

The housing 100 of the cartridge 10 is configured for attachment to the device 600 at the distal end 101 of the housing 100. The cartridge 10 and the device 600 are configured such that when the device 600 and cartridge 10 are mechanically connected, the electrical contacts 221 , 222 of the cartridge electrically connect to corresponding electrical contacts 621 , 622 of the device 600. The electrical contacts 621 , 622 of the device 600 are electrically connected to a power source 630, so that power can be supplied from the power source 630 to the heating element 200. The power source 630 is in the form of a battery, which in this example is a rechargeable lithium ion battery.

The device 600 comprises a controller 640, which is electrically connected to the power source 630. The controller 640 is configured to control the power output from the power source 630, to control whether the heating element 200 is on or off, and to control the temperature of the heating element 200.

In use, air passes into the air inlet 608, through the device body 610, into the air inlet 110 of the cartridge 10, through the aerosol-generating substrate 310, 320 around the heating element 200, at which point an aerosol is formed, the aerosol passing in air flow to the outlet 120 of the cartridge 100, and subsequently to the aerosol outlet 609 of the mouthpiece. The user can draw on the mouthpiece 612 to receive the aerosol from the aerosol outlet 609.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1 . A cartridge for use in an aerosol-generating device, the cartridge comprising: a housing having an inlet and an outlet, and a chamber between the inlet and the outlet; a shredded aerosol-generating substrate within the chamber, the aerosol-generating substrate comprising aerosol former and at least one of tobacco and nicotine; and a planar heating element extending into the chamber, wherein the planar heating element comprises one or more planar heating surfaces for heating the shredded aerosol-generating substrate to form an aerosol and wherein the density of the shredded aerosol-generating substrate within the chamber of the cartridge is at least 0.1 milligram per cubic millimetre of the chamber.

2. A cartridge according to claim 1 , wherein the density of the shredded aerosol-generating substrate within the chamber is at least 0.3 milligrams per cubic millimetre of the chamber.

3. A cartridge according to claim 1 or 2, wherein the shredded aerosol-generating substrate in the chamber is configured to be in direct contact with the one or more planar heating surfaces over a total surface area that corresponds to at least 35 percent of the total cross-sectional area of the chamber in the plane in which the planar heating element extends.

4. A cartridge according to claim 1 or 2, wherein the shredded aerosol-generating substrate is in direct contact with the planar heating surfaces over a total area of at least 40 square millimetres.

5. A cartridge according to any preceding claim, wherein the cut width of the shredded aerosol-generating substrate is at least 0.3 millimetres.

6. A cartridge according to any preceding claim, wherein the shredded aerosol-generating substrate comprises cut filler.

7. A cartridge according to claim 6, wherein the cut filler comprises between 12 percent by weight and 15 percent by weight of aerosol former, on a dry weight basis.

8. A cartridge according to any preceding claim, wherein the aerosol-generating substrate is provided on a carrier element.

9. A cartridge according to any preceding claim, wherein the aerosol-generating substrate comprises homogenised tobacco material.

10. A cartridge according to any of claims 1 to 8, wherein the aerosol-generating substrate comprises an aerosol-generating film comprising a cellulosic based film forming agent, nicotine and aerosol former.

11. A cartridge according to any of claims 1 to 8, wherein the aerosol-generating substrate comprises a gel composition comprising nicotine, at least one gelling agent and aerosol former.

12. A cartridge according to any preceding claim, where the percentage fill of the chamber by the shredded aerosol-generating substrate is at least 50 percent.

13. A cartridge according to any preceding claim, where the cartridge comprises a first shredded aerosol-generating substrate and a second shredded aerosol-generating substrate having a different composition to the first shredded aerosol-generating substrate.

14. A cartridge according to claim 13, wherein the first shredded aerosol-generating substrate and the second shredded aerosol-generating substrate are provided on opposed sides of the planar heating element.

15. An aerosol-generating system comprising a cartridge according to any of claims 1 to 14 and an aerosol-generating device comprising a device cavity for receiving the cartridge.