EP2108456A1 - Device for extracting particles from exhaled breath - Google Patents

Abstract

Device for extracting particles from exhaled breath, comprising a cooling system (16) for creating droplets by condensation of the water vapor contained in the exhaled breath; a droplet collector (7) provided with a side wall (2) having a grid shape and converging towards a flow orifice (9), allowing the droplets attracted to said side wall (2) to flow along the same; ci to the flow orifice (9); and a discharge electrode (1) mounted within the droplet collector (7), said side wall (2) of said droplet collector (7) defining a counter electrode to said discharge electrode (1) for attracting droplets collecting breath-mediated particles exhaled towards said sidewall (2).

Description

The present invention relates to a device for extracting particles from exhaled breath, and more particularly to an electrostatic precipitator for the electrostatic collection of particles carried by exhaled breath.

An electrostatic precipitator (ESP) is an apparatus designed to extract particles from a gas, such as air, using the electrostatic forces produced by an electric field through which these particles pass. The electric field, which is high (several tens of kV per cm) and non-uniform, is induced by two electrodes. In such an electrostatic precipitator, an electric discharge is created within a pocket of less than one millimeter of ionized gas surrounding one of the electrodes, typically in the form of a tip or wire, brought to a high potential negative or positive, a phenomenon called crown effect. The gas pocket is spherical in the case of a point, and cylindrical in the case of a wire. Coming from this pocket, a flow of ions, called ionic wind, sweeps the majority of the inter-electrode space. It covers the particles that are then charged. Sensitive to Coulomb forces, they are driven on the cylindrical or planar counter electrode, grounded.

The efficiency of an electrostatic precipitator is remarkable for all particle sizes with a minimum generally below the micron. Devices operating on this principle can be found commercially (eg United Air Specialists, Inc.). Their advantages are compactness and a yield of about 1 for particles larger than one micron. The main disadvantage of these systems is poor performance in the collection of submicron particles.

In order to improve the efficiency of the electrostatic precipitators in the collection of submicron particles, some electrofilters previously mix the air containing the particles to be collected with water vapor introduced either in the form of droplets or in the form of dry vapor into a unit. upstream of the collection unit. The first case is that of water spray cleaners in which the droplets collect the particles. This type of electrofilter is commercially available, as for example from Wheelabrator Air Pollution Control Inc. The capture of particles results from the fact that they move with the speed of the gas while the droplets have a relative speed with respect to the gas, which can be controlled by different mechanisms, such as for example gravity, inertia and turbulence In the second case, to the previous collection mechanisms is added that related to nucleation. If the injected vapor sees its temperature in the ionic wind zone drop sufficiently below the saturation temperature of the vapor, then the latter condenses around the particles that behave like nucleation sites. The size of the droplets that can carry small particles is thus increased by condensation and the small particles are thus made more sensitive to the electric field. In both cases, although allowing the collection of small particles with a satisfactory yield, these electrostatic precipitators are intended for industrial use and may require in the first case very large quantities of water (several tens liters per hour). They are therefore not suitable for portable applications.

More generally, by their respective sizes, electrofilters described above are not suitable for use allowing an electrostatic collection of particles carried by breath expired in a portable microsystem.

The present invention aims to provide a device compatible with portable use and allowing the extraction of particles of expired breath while having a reduced energy consumption. More particularly, this invention aims to provide a device for the electrostatic collection of pathogens carried by breath expired for subsequent analysis.

This goal is achieved by a system for the analysis of particles extracted from exhaled breath, by a device for extracting particles from exhaled breath, and by an electrostatic precipitator for the electrostatic collection of particles carried by exhaled breath. having the features of the independent claims.

More particularly, this object is achieved by a device for extracting particles from the exhaled breath, comprising a cooling system for creating droplets by condensation of the water vapor contained in the exhaled breath, a droplet recuperator provided with a side wall having a meshed and convergent shape to a flow port, allowing the droplets attracted to said sidewall to flow therealong toward the flow port, and a discharge electrode mounted to the interior of the droplet collector, said sidewall of said droplet collector defining a counter electrode to said discharge electrode for attracting droplets collecting exhaled breath-borne particles to said sidewall.

Thus, a device for extracting expired breath particles compatible with portable use while having reduced energy consumption can be realized.

According to a preferred embodiment, the side wall of the droplet collector comprises a plurality of conductive strips. The conductive lamellae converge towards the flow orifice and are preferably made of metal. Preferably, the conductive strips are spaced from each other in order to perform the roasting function.

The meshed shape allows the exhaled breath to leave the droplet recuperator without constraint. Thus, the exhaled breath can freely exit said droplet recuperator without interfering with the process of collecting droplets capturing particles carried by the expired breath.

According to a preferred embodiment, said droplet recuperator is made in the form of a cone having a tip comprising said flow orifice. The conductive strips are carried by the generatrices of the cone defining the droplet collector. In other words, the conductive lamellae are carried downstream by the tip of the cone and upstream by the base of the cone.

The cone shape advantageously allows the adaptation of the droplet collector for use in a portable system.

The discharge electrode can be made as a tip or a wire. The inner side of the side wall of the droplet collector is preferably made hydrophilic by a surface treatment. This treatment may be a silicon oxide deposit. The inner side of the sidewall of the droplet collector may also be grooved. Its outer side is preferably rendered hydrophobic by a surface treatment.

Thus, the flow of the droplets collecting the breath-mediated particles exhaled along the side wall of the droplet collector to the outlet port of the latter is improved.

The cooling system preferably comprises a chamber having an inner wall, said inner wall being rendered hydrophobic by a surface treatment. Said droplet recuperator is connected downstream of this cooling system.

Thus, the flow of the droplets created by the condensation of the water vapor contained in the breath exhaled along the inner wall of said cooling system chamber to the side wall of the droplet collector is improved.

According to a preferred embodiment, said droplet recuperator is connected to a fluidic microsystem for analyzing the particles, collected by means of the droplets that have flowed along the side wall of said recuperator droplets towards its flow orifice. Preferably, the particles collected are pathogens.

Thus, pathogens carried by exhaled breath can quickly and efficiently be collected and analyzed by a portable system.

The object of the present invention is also achieved by a system for analyzing particles extracted from exhaled breath, comprising a device for collecting expired breath particles and a fluidic microsystem for analyzing the collected particles. The device for collecting expired breath particles includes a cooling system for creating droplets by condensing the water vapor contained in the exhaled breath; a droplet recuperator having a sidewall having a mesh shape and converging toward a flow port allowing the droplets attracted to said sidewall to flow therealong toward the flow port; and a discharge electrode mounted within the droplet recuperator, said side wall of said droplet collector defining a counter electrode to said discharge electrode for attracting droplets collecting exhaled breath-borne particles to said sidewall. The fluidic microsystem for analyzing the collected particles is connected to said device for collecting the particles of exhaled breath at said flow orifice.

The object of the present invention is also achieved by an electrostatic precipitator for the electrostatic collection of exhaled breath particles, comprising a droplet recuperator provided with a side wall having a shape meshed and convergent to a flow port allowing droplets attracted to said sidewall to flow therealong toward the flow port; and a discharge electrode mounted within the droplet collector, said side wall of said droplet collector defining a counter electrode to said discharge electrode for attracting droplets collecting breath-exhaled particles to said sidewall.

• Fig. 1 une vue en perspective d'un système pour l'analyse de particules extraites de l'haleine expirée selon la présente invention,
• Fig. 2 une vue agrandie en coupe d'un électrofiltre pour la collection électrostatique de particules véhiculées par l'haleine expirée selon la présente invention,
• Fig. 3 une vue agrandie en perspective du cône de l'électrofiltre de la Fig. 2, et
• Fig. 4 une vue agrandie en coupe de l'électrofiltre de la Fig. 2 illustrant son principe de fonctionnement selon la présente invention.

The details of embodiment as well as the advantages of the device and of the electrofilter according to the invention will emerge from the following detailed description of an embodiment given by way of example and illustrated by the appended drawings which show schematically:

• Fig. 1 a perspective view of a system for the analysis of particles extracted from exhaled breath according to the present invention,
• Fig. 2 an enlarged sectional view of an electrostatic precipitator for the electrostatic collection of exhaled breath-borne particles according to the present invention,
• Fig. 3 an enlarged perspective view of the cone of the electrofilter of the Fig. 2 , and
• Fig. 4 an enlarged sectional view of the electrofilter of the Fig. 2 illustrating its operating principle according to the present invention.

In the following detailed description of the accompanying drawings, identical elements are designated by identical identification references. In general, these elements and their functionalities are described once for reasons of brevity in order to avoid repetitions. Terms such as "left", "right", "top", "bottom", "bottom", "top", "front" or "behind" may be used in the description of the accompanying drawings. These terms generally refer to a particular location of a component in an associated figure, which may vary from one figure to another.

The Fig. 1 illustrates by way of example a system 10 for the analysis of particles extracted from exhaled breath according to the present invention. Exhaled breath is normally loaded with water vapor and may contain particles, including pathogens such as viruses, bacteria, cells, antibodies, antigens, nucleic acids or other, that one would like to analyze.

According to a preferred embodiment, the system 10 comprises a device 30 for collecting expired breath particles and a fluidic microsystem for analyzing the collected particles 20. The device 30 comprises a cooling system 16 and a droplet recuperator 7 defining an electrostatic precipitator. These are represented in the Fig. 1 by being transparent, for illustration.

The cooling system 16 comprises a chamber 18 having an inner wall 19 which is here, for the illustration, of cylindrical shape. According to a preferred embodiment, the cooling system 16 is positioned upstream of the droplet collector 7 and connected by a connection tight to it. The cooling system 16 is able to cool the water vapor contained in the exhaled breath to obtain droplets by the condensation of water vapor. For the illustration, the expired breath is conveyed to the chamber 18 by a tip 3.

Nevertheless, it should be noted that the particular position and embodiment of the cooling system 16 are not limited to those illustrated in FIG. Fig. 1 , as long as it allows to cool the water vapor contained in the exhaled breath to obtain droplets by condensation. For example, the cooling system 16 and the droplet collector 7 can be combined so that the water vapor contained in the exhaled breath is only cooled from its arrival in the droplet collector 7. Alternatively, the recuperator droplet 7 may be cooled itself, for example by contact and conduction with the cooling system 16. Thus, different embodiments are possible and generally contemplated.

As shows the Fig. 1 the droplet collector 7 has a side wall 2 which preferably defines a convergent shape towards a flow orifice 9 provided at its lower tip 8. The side wall 2 has an inner side 4 and an outer side 5. As described above, below with reference to Figures 2 to 4 , the droplet collector 7 is advantageously of meshed form.

Inside the droplet collector 7 is mounted a discharge electrode 1 which is capable of creating a flow of ions from a pocket of ionized gas surrounding the discharge electrode 1. To allow the creation of such an ion flux, the side wall 2 defines a counter electrode to the discharge electrode 1. Thus, droplets capable of collecting particles carried by the breath are expired are carried by the flow of ions from the location of the discharge electrode 1 to the side wall 2 of the droplet collector 7. During their journey, these droplets capture particles to collect and take them to the side wall 2 or the droplets with the captured particles form a liquid film 6 flowing along the side wall 2 to and through the flow port 9 in the microsystem 20.

According to a preferred embodiment, the flow orifice 9 is adapted to a respective inlet of the microsystem 20. This is connected to the device 30, for example by gluing, to recover the collected particles.

The microsystem 20 comprises a silicon substrate 21 having fluidic chambers and channels, such as the chambers 22, 23 and the channel 24. These can be generated by conventional silicon photolithography and etching techniques on or in the upper face of the substrate 21. According to the need or the analysis protocol of a respective sample to be collected via the device 30, the fluidic chambers 22, 23 and the channel 24 can be provided with a depth of the order of 10 to 500 μm.

The fluidic part of the microsystem 20 is sealed by assembling above the substrate 21 a silica wafer 40 pierced with holes serving as input-output of the microsystem 20. The silica wafer 40 may alternatively be made of glass, plastic or any other material making the microsystem 20 waterproof. The assembly of the wafer 40 and the substrate 21 can be made irreversible by a deposit of adhesive on the substrate 21 around the fluidic parts of the component, that is to say around the chambers 22, 23 and the channel 24. This glue deposit is made for example by screen printing of glue. A suitable process is described in the patent FR 2,856,047 .

Thus, multiple microsystems 20 can be assembled on a single wafer as described above. The assembly thus completed, this wafer can be cut into individual components by cutting with a saw adapted.

Nevertheless, it should be noted that the production of fluidic microsystems adapted to the analysis of particles collected from exhaled breath is known to those skilled in the art. Thus, a more detailed description of the microsystem and its operation is omitted for the sake of brevity.

The Fig. 2 shows the device 30 for collecting particles from the exhaled breath of the Fig. 1 in enlarged sectional view. As shows the Fig. 2 , the chamber 18 of the cooling system 16 is made hermetic with respect to the nozzle 3 by means of a seal 17 and the discharge electrode 1 is a tip 15.

Alternatively, the discharge electrode 1 can be made as a wire, especially a polarized wire. Such a wire will generate a larger discharge area than tip 15, since the corresponding discharge zone would be around the entire length of the wire, thus allowing collection of the expired breath particles. By way of example, a discharge voltage of 10 KV could be applied to a wire having a diameter of 50 μm in order to create a suitable discharge zone. This voltage can be increased for a wire having a larger diameter. It can be decreased for a wire having a smaller diameter, for example a wire having a diameter of 10 microns.

According to one embodiment, the wire is made of a mechanically resistant conductive material, such as for example tungsten. Preferably, the material used is also weldable, such as copper. Such a wire will preferably be positioned parallel to the axis of the droplet collector 7, preferably parallel to its central axis, and fixed by support means in its position, said support means being for example pressed against the side 4 inside the side wall 2 and joining the ends of the wire to it without hindering the flow of collected droplets. According to one embodiment, three coplanar supports spaced approximately 60 ° apart from one another, thus constituting a star-shaped support, serves as support means at each end of the wire.

As mentioned above, according to a preferred embodiment the droplet collector 7 of the device 30 is of meshed form. Its side wall 2 comprises, for example, a plurality of conductive strips 34 converging towards the flow orifice 9. These are preferably interconnected by struts 37, and spaced apart from gaps 35. The conductive strips 34 define a counter-electrode to the discharge electrode 1 and are preferably made of metal.

The interstices 35 are oversized to clarify their realization. Nevertheless, it is necessary to make the interstices 35 so that the droplets carried to the side wall 2 can flow to the flow orifice 9 along the side wall 2 without constraint and that the exhaled breath, that is to say any non-condensable gas, can exit the recuperator of droplets 7 without constraint.

The Fig. 3 shows the droplet collector 7 of the Fig. 1 in enlarged perspective view. This clarifies the meshed form of the recuperator 7 with the conductive lamellae 34, the interstices 35 and the struts 37. Only a portion of the conductive lamellae 34 and interstices 35 have been designated by identification references for the sake of clarity of the invention. representation.

As shows the Fig. 3 , the droplet collector 7 is preferably conically shaped with a base 32 and the tip 8 having the flow orifice 9. The conical shape of the recuperator 7 is defined by the generatrices of the cone carrying the conductive strips 34. the example shown in the Fig. 3 , the conductive strips 34 represent generatrices of the cone and are then carried downstream by the tip 8 of the cone and upstream by its base 32, that is to say by the downstream portion of the cooling system 16 of the Fig. 2 .

The above-mentioned embodiment of the droplet collector 7, and in particular its conical shape, has the advantage of constituting on its inner side 4 a surface, which is not arranged parallel to the expired breath and therefore to the trajectory of the particles. conveyed by it. This surface and the meshed form of the droplet collector 7 then promote the passage of particles in the vicinity of at least one of the conductive strips 34, thereby increasing the collection efficiency of the droplet collector 7, unlike a structure disposed parallel to the trajectory of the particles carried by the expired breath.

Nevertheless, it should be noted that other embodiments are possible. For example, conductive lamellae 34 may be made in a circular, spiral, chevron or other shape as long as the functionality described in the context of the present invention is ensured. Thus, all these different modes of execution are contemplated.

It should be noted that the droplet collector 7 illustrated in FIG. Fig. 3 comprises a plurality of struts 37 as an example. Nevertheless, according to a preferred embodiment the conductive strips 34 are held only by a first strut provided near the base 32 and a second strut provided near the tip 8 of the droplet collector 7, preferably starting from the lower end. of the last. In other words, the number and the location of the struts 37, which serve essentially to maintain the structure of the cone chosen to produce the recuperator 7, can be modified without changing the functionality of the droplet collector 7.

To realize the droplet collector 7 of the Fig. 3 in the form of a cone, several techniques are conceivable and contemplated. For example, a suitable size cone of stamped aluminum alloy can be used. In this cone, lateral discharge slots defining the interstices 35 as well as the flow orifice 9 at the tip 8 of the cone are made by laser cutting.

The Fig. 4 illustrates the principle of operation of the device 30 of the Fig.1 according to the present invention. According to a mode preferred embodiment, the expired breath 60 is conveyed to the cooling system 16 by the nozzle 3. The expired breath 60 is charged with steam and contains particles to collect 66.

In the cooling system 16, the exhaled breath 60 is cooled to obtain condensation water vapor droplets. These droplets are carried to the side wall 2 of the droplet collector 7 by a flow of ions generated from an ionized gas bag 50 surrounding the tip 15 of the discharge electrode 1. During their journey, designated for the illustration by arrows 70, the droplets obtained capture particles 66 and take them to the side wall 2.

Arriving at the side wall 2, the droplets form a liquid film 6 flowing along the side wall 2 to the flow orifice 9. The operation of an electrostatic precipitator as defined by the device 30 is generally known. by those skilled in the art, a more detailed description is omitted here.

To improve the operation of the device 30, the inner side 4 of the side wall 2 of the droplet collector 7 can be rendered hydrophilic by a surface treatment, for example by a silicon oxide (SiO ₂ ) deposit. The inner side 4 can also be structured by grooving oriented in the direction of flow of the droplets, the grooving helping to channel the flow. In addition, its outer side 5 can be rendered hydrophobic by a surface treatment. With regard to the cooling system 16, the inner wall 19 of its chamber 18 can also be rendered hydrophobic by a surface treatment.

Although a particular embodiment is described above, multiple variations can be made to the clasp according to the invention without altering its functionality. As a result, all these variations are also considered and generally contemplated.

Claims (22)

Device for extracting particles from exhaled breath, comprising: a cooling system (16) for creating droplets by condensation of the water vapor contained in the expired breath; a droplet collector (7) provided with a side wall (2) having a grid shape and converging towards a flow orifice (9), allowing the droplets attracted to said side wall (2) to flow along the same; ci, to the outlet (9); and a discharge electrode (1) mounted within the droplet collector (7), said side wall (2) of said droplet collector (7) defining a counter electrode to said discharge electrode (1) for attracting droplets collecting particles carried by the exhaled breath to said side wall (2). Device according to claim 1, wherein the side wall (2) of the droplet collector (7) comprises a plurality of conductive strips (34). Device according to claim 2, wherein the conductive lamellae (34) converge towards the discharge orifice (9). Device according to claim 2 or 3, wherein the conductive lamellae (34) are made of metal. Device according to one of claims 2 to 4, wherein the conductive strips (34) are spaced the each other to let the exhaled breath out of the droplet collector (7) without constraint. Apparatus according to any one of the preceding claims, wherein said droplet collector (7) is cone-shaped having a tip (8) having said flow orifice (9). Device according to one of claims 2 to 6, wherein the conductive strips (34) are carried by the generatrices of the cone defining the droplet collector (7). Apparatus according to any one of the preceding claims, wherein the discharge electrode (1) is a tip or wire. Device according to any one of the preceding claims, wherein the inner side (4) of the side wall (2) of the droplet collector (7) is made hydrophilic by a surface treatment. An apparatus according to claim 9, wherein the treatment is a silicon oxide deposit. Device according to any one of the preceding claims, wherein the inner side (4) of the side wall (2) of the droplet collector (7) is grooved. Device according to any one of the preceding claims, in which the outer side (5) of the side wall (2) of the droplet collector (7) is rendered hydrophobic by a surface treatment. Apparatus according to any one of the preceding claims, wherein the cooling system (16) comprises a chamber (18) having an inner wall (19), said inner wall (19) being rendered hydrophobic by a surface treatment. Apparatus according to any one of the preceding claims, wherein said droplet collector (7) is connected downstream of the cooling system (16). Apparatus according to any one of the preceding claims, wherein said droplet recuperator (7) is connected to a fluidic particle analysis microsystem (20), collected by means of droplets which have flowed along the side wall (2) said droplet collector (7) to its flow orifice (9). Apparatus according to any one of the preceding claims, wherein the particles (66) are pathogens. System for the analysis of particles extracted from exhaled breath, comprising: a device (30) for collecting particles of exhaled breath, comprising: a cooling system (16) for creating droplets by condensation of the water vapor contained in the expired breath; a droplet collector (7) provided with a side wall (2) having a mesh shape and converging towards a flow orifice (9), allowing the droplets attracted to said side wall (2) to flow therealong towards the outlet (9); a discharge electrode (1) mounted within the droplet collector (7), said side wall (2) of said droplet collector (7) defining a counter electrode to said discharge electrode (1) for attracting droplets collecting particles carried by the exhaled breath to said side wall (2); and a fluidic microsystem for analyzing the collected particles (20), said microsystem (20) being connected to said device (30) for collecting the particles of exhaled breath at said flow port (9). The system of claim 17, wherein said device (30) for collecting the expired breath particles is made according to any one of claims 2 to 14. Electrostatic precipitator for the electrostatic collection of expired breath particles, comprising: a droplet collector (7) provided with a side wall (2) having a grid shape and converging towards a flow orifice (9), allowing the droplets attracted to said side wall (2) to flow along the same; ci, to the outlet (9); and a discharge electrode (1) mounted within the droplet collector (7), said side wall (2) of said droplet collector (7) defining a counter electrode to said discharge electrode (1) for attracting droplets collecting particles carried by the exhaled breath to said side wall (2). An electrostatic precipitator according to claim 19, wherein said droplet collector (7) is cone-shaped having a tip (8) having said flow port (9). An electrostatic filter according to claim 20, wherein the side wall (2) of the droplet collector (7) comprises a plurality of conductive lamellae (34), said conductive lamellae (34) being carried by the generators of the cone defining the droplet collector ( 7). Electrostatic filter according to one of claims 19 to 21, wherein said droplet collector (7) is cooled to create the droplets by condensation of the water vapor contained in the exhaled breath.

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