WO2024012825A1

WO2024012825A1 - Test strip cassette, monitoring device and method for fabricating a test strip cassette

Info

Publication number: WO2024012825A1
Application number: PCT/EP2023/066757
Authority: WO
Inventors: Giuliano Manzi; Boon Chong CHEAH; Axel Schubert
Original assignee: Ams Osram AG
Current assignee: Ams Osram AG
Priority date: 2022-07-13
Filing date: 2023-06-21
Publication date: 2024-01-18
Anticipated expiration: 2025-01-13

Abstract

A test strip cassette (1) is disclosed that comprises a housing (20) defining a first opening (21) being configured to receive a sample liquid, the housing (21) further defining a second opening (22) and a third opening (23) which form a pass-through configured to provide an optical path through the housing (20). The test strip cassette (1) further comprises a test strip (10) arranged inside the housing (20) that comprises a sample pad (14) aligned with the first opening (21) and an active area (11) aligned with the passthrough. Further, a monitoring device (100) is disclosed comprising the test strip cassette (1).

Description

TEST STRIP CASSETTE , MONITORING DEVICE AND METHOD FOR FABRICATING A TEST STRIP CASSETTE

The present disclosure relates to a test strip cassette , a monitoring device and a method for fabricating a test strip cassette .

BACKGROUND OF THE INVENTION

A test strip cassette is a part of a monitoring device . The test strip cassette can be inserted before a test or measurement and removed after the test or measurement . The monitoring device is typically portable and, thus , can be used for point-of-care applications in medical diagnostics and environmental tests . The test strip cassette can be used for a lateral flow test . The test strip cassette comprises a test strip of porous material and uses the capillary action of the porous material and its ability to bind marker molecules .

A sample liquid such as water, urine , blood or another liquid is provided to the test strip . The sample liquid flows using the capillary ef fect of the porous material and performs a chemical reaction . The chemical reaction may result in a change of color at a predetermined active area of the porous material . The active area may have the form of a narrow or broad line . There may be reactions at two active areas , respectively lines , of the porous material .

Change of color may be monitored by visual inspection . These class of tests have several advantages , but there are still some disadvantages related e . g . to sensitivity and multianalyte detection . Another class of tests may be equipped with a photodetector and/or a light source inside the test strip cassette that allows automatic monitoring of color change . In this case , however, assembly may be complicated and it might be necessary to dispose the photodetector and the light source together with the test strip after usage . From an environmental and cost perspective , this could be disadvantageous . Finding a solution for these drawbacks may bring more tests to a home environment .

It is an obj ect to provide a test strip cassette , a monitoring device and a method for fabricating a test strip cassette that allow reliable read-out of measurement results as well as simple and cost-ef fective assembly and usage .

These obj ects are achieved by the subj ect-matter of the independent claims . Further developments and embodiments are described in the dependent claims .

SUMMARY OF THE INVENTION

In an embodiment , a test strip cassette comprises a housing . The housing defines a first opening being configured to receive a sample liquid . The housing further defines a second opening and a third opening that form a pass-through . The pass-through is configured to provide an optical path through the housing . The test strip cassette further comprises a test strip arranged inside the housing . The test strip comprises a sample pad aligned with the first opening . The test strip further comprises an active area aligned with the pass- through . The housing may be a molded compound . The housing can be made of plastic, for example . The sample pad is aligned with the first opening of the housing . This can mean that in the vertical direction the sample pad is arranged under the first opening . In the lateral directions the region of the sample pad has an overlap with the region of the first opening .

Thus , the sample liquid can be inserted via the first opening onto the sample pad of the test strip .

The test strip has a fixed position within the housing . The at least one active area, the second opening and the third opening are aligned with each other . This can mean that in a vertical direction, which runs perpendicular to a main plane of extension of the test strip, the at least one active area is arranged between the second opening and the third opening of the housing . In lateral directions which run parallel to the main plane of extension of the test strip, the region of the active area overlaps the region of the second opening and the region of the third opening . Thus , an optical path is provided such that light can be transmitted through the second opening, the active area of the test strip and the third opening . The second opening can be arranged on the top side of the housing, while the third opening can be arranged on the bottom side of the housing, or vice-versa . The second opening and the third opening provide a pass-through through the housing . This can mean that the pass-through provides an optical path from a top side of the housing to an opposite bottom side of the housing . A part of the test strip, in particular the region comprising the active area, is arranged in said pass-through and is therefore exposed from two sides . The pass-through may be referred to as through-hole or passage . The test strip cassette can be free from a light source and a photodetector . This can in particular mean that light sources and photodetectors are not arranged inside the housing . A light source and a photodetector for transmittance measurements may be comprised by an external reading device , also called monitoring device , as described below . Thus , the test strip cassette can be manufactured at low cost . Further, since the active area is exposed from two sides of the housing, the test strip cassette can be used for transmittance measurements , where a light source is arranged on one side of the housing and a photodetector is arranged on the other side . The photodetector can detect the light transmitted by the active area . Thus , a color change and/or and change in intensity can be detected by the photodetector . Alternatively, the measurement may be based on fluorescence or phosphorescence . In this case , light is emitted by the light source in one wavelength region and is absorbed by a substance in the active area, wherein the substance in the active area emit light of another wavelength region . Also here , the light source may be arranged on one side of the housing and the photodetector may be arranged on the other side . This arrangement enables higher alignment tolerances compared to arrangements , where the light source and the detector are arranged on the same side of the test strip ( reflectance measurements ) . As a result , the position of the active area on the test strip does not have to be exactly aligned with the position of the detector, which reduces manufacturing costs of such test strips . The positioning of the active area on the test strip has larger tolerances .

In an embodiment , the test strip comprises a porous material , in particular nitrocellulose , which is configured to trans fer the sample liquid from the sample pad to the active area . In an embodiment , the active area is provided with a chemical substance which reacts with a component of the sample liquid to provide a color change of the active area . Alternatively, the reaction darkens or brightens the active area, so that more or less light is transmitted through the active area . In even another alternative , the reaction enables fluorescence or phosphorescence at the active area .

The component may be an analyte included in the sample liquid . The porous material may comprise nitrocellulose . The porous material may be bibulous . The porous material may be covered by a film . The film may protect the porous material . The film may be transparent or translucent . Transparent may be named also optically clear . The porous material may have a speci fic ratio of pore si ze , porosity and thickness plus a dedicated chemical treatment . Advantageously, the capillary action of the porous material can be used to transport the sample liquid .

The sample pad of the test strip may provide the sample liquid to the porous material directly or via a conj ugate pad of the test strip . The conj ugate pad includes e . g . a chemical substance ( typically a chemical compound) designed for reaction with an analyte included in the liquid .

In an embodiment , the test strip further comprises an absorbing pad for absorbing excess liquid from the porous material . In an embodiment , the sample pad, the conj ugate pad and the absorbing pad are also reali zed by a porous film or a porous layer, which is made of nitrocellulose , for example .

In an embodiment , the porous material including the sample pad, the conj ugate pad, the active area and the absorbing pad are arranged on a first side of a substrate . The substrate may be comprised by the test strip . The substrate may be fabricated as a backing card, for example as a plastic adhesive backing card . The substrate may be made of plastic or a polymer such as polycarbonate ( PC ) , polystyrene ( PS ) , polyethylene , polyethylene terephthalate ( abbreviated PET ) , vinyl , polyester, polyimide , acrylamide , epoxy resin or a woven fiberglass cloth impregnated with an epoxy resin

(usually named FR-4 glass epoxy) or glass . The substrate may be optically transparent . By using the substrate the test strip may exhibit an enhanced sti f fness . Moreover, the test strip can be built in a stacked structure .

In an embodiment , the test strip comprises at least one additional active area aligned with the pass-through . All features of the active area are also disclosed for and applicable to the additional active area . The additional active area may be provided with another chemical substance . The chemical substance the additional active area is provided with may react with another component of the sample liquid to provide a color change , a change of intensity of transmitted light or f luorescence/phosphorescence at the active area . The color change of the additional active area may be di f ferent from the color change of the active area . The region of the test strip comprising both the active area and the additional active may be exposed by the second opening at one side and the third opening at another side , so that the active area and the additional active area are placed in the same pass- through defined by the housing .

Alternatively, the additional active area is aligned with an additional pass-through defined by the housing . For example , the additional pass-through is formed by an additional pair of opening, e . g . a fourth and a fi fth opening defined by the housing . The additional pass-through is configured to provide an additional optical path from the top side of the housing to the opposite bottom side of the housing . All features of the pass-through are also disclosed for and applicable to the additional pass-through .

In an embodiment , each additional active area is assigned to a respective additional pass-through . By means of multiple active areas that are exposed by the same or di f ferent passthroughs , multiple analytes can be measured with the same test strip . Separate pass-throughs ( i . e . pairs of openings ) can be used to prevent cross-talk between those measurements .

In an embodiment , at least of one of the openings of the pass-through defined by the housing tapers towards the active area of the test strip . This can mean that a diameter of the second opening and/or the third opening becomes smaller towards the at least one active area . For example , the second opening and/or the third opening describe a conical or parabolic shape . In other words , a sidewall of the second opening and/or the third opening is inclined with respect to the vertical direction . Light rays from a light source at an input side of the pass-through can be coupled into the housing under a wide angle . Further, the light rays can be reflected at the sidewall of the opening once or multiple times . Thus , the light rays are ef fectively collimated, so that the intensity of light at the active area is increased . On the other side , light rays transmitted/emitted by the active area can reach a photodetector under a wide angle , thus increasing the sensitivity . In other words , the draft angle of the aperture defined by the pass-through varies to collimate and focus light . Thus , light collection ef fectiveness and light collimation can be increased . Advantageously, a refractive lens is not required to increase light collection ef fectiveness and light collimation . Thus , a low cost and lens free arrangement is provided to improve light collection ef fectiveness and sensitivity . This also allows the tolerance of the distance between the active area and the photodetector to be more relaxed .

In case that the test strip comprises a plurality of active areas ( i . e . at least one additional active area ) , each active area may be provided with a separate additional pass-through, as mentioned above . Each of the pass-throughs may taper towards the respective assigned active area .

In an embodiment , a sidewall of at least one of the openings of the pass-through defined by the housing is coated with a reflective layer . The reflective layer may be arranged exclusively at the sidewall of the opening, i . e . at an inner surface of the pass-through . Thus , a reflective surface is provided at the sidewall . The reflective layer may be a lacquer, by way of example . By means of the reflective layer light rays are better reflected at the sidewall and light collimation/collection is increased .

Furthermore , a monitoring device is provided that comprises the tests strip cassette as discussed above . This means that all features disclosed for the test strip cassette are also disclosed for and applicable to the monitoring device and vice-versa .

In an embodiment , the monitoring device comprises the test strip cassette , a light source and a photodetector . The test strip cassette is arranged between the light source and the photodetector, such that the pass-through defined by the housing of the test strip cassette and the active area of the test strip are aligned with the light source and the photodetector . This can mean that the active area in the pass-through is arranged within a light cone emitted by the light source and received by the photodetector . Thus , transmittance measurements are enabled .

In an embodiment , the monitoring device further comprises at least one additional light source , wherein each additional light source is assigned to a respective additional active area of the test strip . Each additional light source may also be assigned to a respective additional pass-through defined by the housing . Advantageously, the active area and each additional active area can be illuminated uni formly and with a high exposure intensity . The light source and the additional light source ( s ) may emit light in the same wavelength region . It is also possible that the light source and the additional light source ( s ) emit light in di f ferent wavelength regions , depending on the analyte to be detected at the respective active area . It is also possible that groups of active areas are assigned to a common light source or that groups of light sources are assigned to a common active area .

In an embodiment , the monitoring device further comprises at least one additional photodetector, wherein each additional photodetector is assigned to a respective additional active area of the test strip . Each additional photodetector may be also be assigned to a respective additional pass-through defined by the housing . Advantageously, the active area and each additional active area can be monitored by its own photodetector to increase sensitivity . It is also possible that groups of active areas are assigned to a common photodetector or that groups of photodetectors are assigned to a common active area.

In an embodiment, the photodetector and the additional photodetector are configured to detect light in different wavelength regions. The photodetector and the additional photodetector ( s ) may detect light in different wavelength regions, depending on the analyte to be detected. It is also possible that the photodetector and the additional photodetector ( s ) may detect light in the same wavelength region or that groups of photodetectors detect light in the same wavelength region, while other groups of photodetectors detect light in different wavelength regions. In an embodiment, the monitoring device comprises a photodetector with a plurality of pixels. For example, the pixels are arranged in a one- or two-dimensional array. Each pixel of the array may be assigned to a respective active area or additional active area, respectively. If the monitoring device comprises a plurality of photodetectors or a plurality of pixels, which are configured to detect different wavelengths, it is possible to detect different analytes. It is also possible to enable both transmittance and fluorescence measurements at the same test strip.

In an embodiment, the monitoring device is configured such that the test strip cassette is selectively insertable into and removable from the monitoring device. Thus, the test strip cassette is used once, namely for a single test. The monitoring device is designed to be used several times, e.g. with different test strips for detecting different analytes or with test strips for detecting the same analyte. In an embodiment , the monitoring device further comprises a control circuit , wherein the control circuit is configured to detect whether the test strip cassette is inserted or not and to provide an enable signal , when the test strip cassette is inserted . By generating the enable signal , the monitoring device may be able to detect the correct insertion of the test strip cassette into the monitoring device or/and may be able to detect whether the correct test strip cassette is inserted . For example , the control circuit detects insertion of the test strip cassette by means of a position sensor comprised by the monitoring device , to which the control circuit is electrically connected . The position sensor may be an optical or mechanical or electrical or magnetic position sensor, which means that the position sensor detects the test strip cassette by optical or mechanical or electrical or magnetic means . It is also possible that the light source and the photodetector serve as position sensor, such that no additional position sensor is needed . However, i f an additional position sensor is used, the photodetector and the light source can be spared and the power consumption can be reduced .

In an embodiment , the light source is arranged on a carrier and the photodetector is arranged on a further carrier . The carrier and the further carrier may be connected by an electrical connection . For example , the carrier and the further carrier are arranged parallel to each other, wherein the test strip cassette is arranged in between . For example , the carrier and the further carrier are implemented as printed circuit board ( PCB ) . For example , the electrical connection is implemented as flex cable . In case of additional light sources these can be arranged on the carrier as well . In case of additional photodetectors these can be arranged on the further carrier as well . Advantageously, the light source or the plurality of light sources and the photodetector or the plurality of photodetectors can be controlled simultaneously .

In an embodiment , the light source and the photodetector are synchroni zed . This can mean that the light source is activated only i f the photodetector is active or vice-versa . Accordingly, the light source is deactivated i f the photodetector is not active or vice versa . For example , the photodetectors are active during a light pulse lasting approximately 200 ms . Alternatively, the photodetectors are activated with a time delay to the light sources . Here , there is a time gap between the activation of the light source and the activation of the photodetectors . For example , a light pulse of approximately 2 ms is followed by a pause of 100 ps , which in turn is followed by a sensing time of approximately 4ms . This mode is preferably used for fluorescence measurements to detect di f ferent substances based on their speci fic radiation characteristics in the time domain . The time scheme example above would be suitable to detect fluorescence with a decay time of ~ lms and to discriminate it from typical background fluorescence in the range of approximately 5ns . It is therefore possible to detect di f ferent substances not only on the basis of di f ferent emitted wavelengths , but also on the basis of their time resolution . It is also possible that the light source and the photodetector are only activated i f the test strip cassette is inserted into the monitoring device . Power consumption can be reduced by means of synchroni zation of the light source and the photodetector . In an embodiment , the active area is arranged on a side of the test strip which, when the tests strip is inserted in the monitoring device , faces the light source or, respectively, the carrier on which the light source is arranged . This can mean that the active area faces the second opening of the housing, such that the active area is visible through the second opening . Advantageously, a test result can also be determined by visual inspection, additionally to evaluation of the photodetector signal . Further, light rays are not scattered by further components before reaching the active area . For example , light rays are not scattered by the backing card/ substrate on which the active area is arranged . For example , the transmission of the substrate may depend on the wavelength of the used light source . At short wavelengths in the UV range , the substrate may absorb more radiation than at wavelengths in the visible range . For example , a substrate made of polycarbonate ( PC ) may absorb radiation of 350 nm or less , while a substrate made of polystyrene ( PS ) may absorb radiation of 300 nm or less . Thus , i f an ultraviolet light sources ( e . g . for fluorescence measurements ) and a substrate of one of the above materials is used, it might be desired to arrange the substrate under the porous material with the active area, such that the substrate faces the photodetector . In this way an improved sensitivity is achieved for wavelengths in the UV range .

Alternatively, the active area is arranged on a side of the test strip which, when the test strip cassette is inserted in the monitoring device , faces the photodetector or, respectively, the further carrier on which the photodetector is arranged . This can mean that the substrate/ backing card faces the light source . In this way, the performance of a transmission measurement may be improved because the active area is closer to the photodetector and a color change/ intensity change of the active area is not distorted by the substrate of the test strip . Thus , an improved sensitivity may be achieved for wavelengths larger than e . g . 350 nm or for wavelengths in the visible range .

Furthermore , a method for producing a test strip cassette is provided . All features disclosed for the test strip cassette are also disclosed for and applicable to the method for fabricating the test strip cassette and vice-versa .

In an embodiment , the method for fabricating a test strip cassette comprises providing a housing defining a first opening being configured to receive a sample liquid . The housing further defines a second opening and a third opening that form a pass-through configured to provide an optical path through the housing . The method further comprises providing a test strip comprising a sample pad and an active area . The method further comprises assembling the housing and the test strip, such that the housing encloses the test strip and the sample pad is aligned with the first opening and the active area is aligned with the pass-through .

The test strip cassette can be manufactured at low cost , as the test strip cassette can be free from a light source and a photodetector . Further, since the active area is exposed from two sides of the housing, the test strip cassette can be used for transmittance measurements , where a light source is arranged on one side of the housing and a photodetector is arranged on the other side .

Further embodiments of the method become apparent to the skilled reader from the embodiments of the test strip cassette described above. For example, the method for fabricating a test strip cassette may be implemented by the test strip cassette and the monitoring device according to one of the embodiments defined above.

The test strip cassette is configured for an optical assay reading device. The test strip cassette is configured for a lateral flow test system, abbreviated as LFT system. The LFT system performs refracted and/or transmitted and/or absorbance and/or fluorescence measurements.

The disclosure applies to the field of lateral-flow-test for point-of-care (abbreviated PoC) . The test strip in the test strip cassette reacts to a certain substance that is present in the liquid under test, and color of the porous active area, realized e.g. by depositing conjugated antibodies on the nitrocellulose membrane, changes accordingly when analytes bind to conjugated antibodies. The liquid under test may be named sample, sample liquid or analyte. Alternatively, the substance to be detected is called analyte. The substance to be detected may be a chemical element or a chemical compound .

An example of an application is a home pregnancy test. The test is e.g. able to detect human chorionic gonadotropin (HCG) in urine of a pregnant women. The test assay utilizes the capillary action of porous paper and the ability to bind marker proteins to the cellulose. Usually a two line pattern is used. The first line generates a yes/no signal (pregnant or not) . The second line indicates if the test is successful or not. Point-of-care tests (PoC tests) have the ability to test a patient at the point where the care is necessary. This allows a faster diagnosis, hence a faster treatment. Other important applications are tests for identi fying diseases . Especially in the case of an outbreak of a global pandemic, such as Covidl 9 , it can be important to provide tests that can quickly determine whether the tested person is infected or not . Moreover, such tests can be performed by anyone at home , thus saving the resources of public laboratories . The test strip cassette can be manufactured inexpensively and ef fectively, ensuring rapid and worldwide distribution .

Normally, the LET is read ( analyzed) by the human eye , and is therefore not able to accurately measure concentration variations . Lateral flow tests also known as lateral flow immunochromatographic assays are ef fective devices intended to detect the presence ( or absence ) of a target analyte in a sample (matrix ) without the need for speciali zed and costly equipment , though many lab based applications exist that are supported by reading equipment . Typically, these tests are used for medical diagnostics either for home testing, point of care testing or laboratory use .

The test strip cassette described in the present disclosure aims to improve system performance , e . g . an increase of reading accuracy and better quantitative analysis . For that , the test strip inside the test strip cassette is exposed on two opposite sides . Thus , the test strip cassette enable to arrange a light source on one side and a photodetector on the other side . The arrangement of the photodetector and the light source inside a reading device helps to reduce cost at the customer side , since the test strip cassette , which can only be used once , can be manufactured at low cost . BRIEF DESCRIPTION OF THE DRAWINGS

The following description of figures may further illustrate and explain aspects of the test strip cassette , the monitoring device and the method for fabricating a test strip cassette . Components and parts of the test strip cassette that are functionally identical or have an identical ef fect are denoted by identical reference symbols . Identical or ef fectively identical components and parts might be described only with respect to the figures where they occur first . Their description is not necessarily repeated in successive figures .

Figure 1 shows an exemplary embodiment of a test strip cassette ;

Figure 2 shows another exemplary embodiment of a test strip cassette ;

Figure 3 shows another exemplary embodiment of a test strip cassette ;

Figure 4 shows an arrangement according to a further embodiment ;

Figure 5 shows an exemplary embodiment of a test strip cassette and a monitoring device ;

Figure 6 shows another exemplary embodiment of a test strip cassette and a monitoring device ;

DETAILED DESCRIPTION

Figure 1 shows an example of the test strip cassette 1 in a cross-sectional view . The test strip cassette 1 comprises a housing 20 and a test strip 10 . The housing 20 may be fabricated as a plastic holder . The housing 20 defines a first opening 21 being configured to receive a sample liquid . This means that the sample liquid can be inserted via the first opening 21 of the housing 20 onto the test strip 10 . The first opening 21 of the housing 20 may also be called sample port . The housing 20 further defines a second opening

22 and a third opening 23 forming a pass-through configured to provide an optical path from a top side of the housing 20 to an opposite bottom side of the housing 20 . In the shown embodiment the second opening 22 is arranged at the top of the housing 20 , while the third opening 23 is arranged at the bottom of the housing 20 opposite the second opening 22 .

The test strip 10 is arranged inside the housing 20 . The test strip 10 comprises a sample pad 14 aligned with the first opening 21 and an active area 11 aligned with the pass- through, i . e . the second opening 22 and the third opening 23 . Light emitted by a light source 31 , that is not part of the test strip cassette 1 , can reach the test strip 10 inside the housing 20 via the second opening 22 . Further, the light can be absorbed or transmitted by the active area 11 of the test strip 10 . Finally, light can be transmitted or emitted by the active area 11 and leave the housing 20 via the third opening

23 to fall onto a detector 41 , which is not part of the test strip cassette 1 .

The test strip 10 comprises a porous material , in particular nitrocellulose . The porous material may be implemented as porous layer 18 . The active area 11 is embedded in the porous material . The porous material is configured to trans fer the sample liquid from the sample pad 14 to the active area 11 . The active area 11 is provided with a chemical substance which reacts with a component of the sample liquid . This reaction results in a color change of the active area 11 or darkens/brightens the active area 11 , such that more or less light is transmitted by the active area 11 . Alternatively, the reaction enables f luorescence/phosphorescence at the active area 11 , such that the light emitted by the light source 31 is absorbed by the active area 11 and light of another (usually larger ) wavelength is emitted by the active area 11 . The optical characteristic of the active area 11 depends inter alia on the concentration of an analyte in the sample liquid . For example , the light source 31 emits light in a broad spectrum . The active area 11 transmits or emits light only in a small spectrum such as , for example , red light . The light transmitted/emitted by the active area 11 is detected by the photodetector 41 .

The porous material may be translucent or transparent . The porous material has the form of a layer, membrane , film or sheet . The porous material may be made of nitrocellulose . The porous material may be fabricated as a nitrocellulose membrane . The porous material is configured such that a liquid can laterally flow in the porous material . The flow of the liquid is performed using a capillary ef fect in the porous material . The liquid may be named sample liquid .

Apart from the sample pad 14 and the active area 11 the test strip 10 shown in Fig . 1 further comprises a conj ugate pad 15 and an absorbent pad 16 . The sample pad 14 , the conj ugate pad 15 and the absorbent pad 16 are arranged at main side of a substrate 17 and enclose the side surfaces of the porous material . The substrate 17 may be translucent or transparent . Thus , light from or transmitted by the active area 11 can reach the photodetector 41 . The conj ugate pad 15 is reali zed for providing a substance to the sample liquid. The conjugate pad 15 is located on the main side of the substrate 17. The conjugate pad 15 is arranged between the sample pad 14 and the porous material. The sample pad 14 overlaps the conjugate pad 15. Thus, an effective transfer of liquid from the sample pad 14 to the conjugate pad 15 is achieved by the overlap. The conjugate pad 15 overlaps the porous material. An efficient transfer of liquid from the conjugate pad 15 to the porous layer 18 is achieved by the overlap. The sample pad 14 and the conjugate pad 15 are located at a first end of the test strip 10.

The absorbent pad 16 is arranged at a second end of the test strip 10. The absorbent pad 16 is in contact with the porous material, i.e. the porous layer 18. The absorbent pad 16 has an overlap with the porous material. Thus, a transfer of liquid is achieved from the porous material to the absorbent pad 16 by the overlap. The liquid flows from the sample pad 14 via the conjugate pad 15 and the porous material 18 to the absorbent pad 16. The sample liquid inserted on the sample pad 14 only partially reaches the absorbent pad 16. This means that only excess liquid is absorbed by the absorbent pad 16.

In general, the test strip 10 is built in a stacked structure: The test strip 10 includes the substrate 17. The material of the substrate 17 is made e.g. of polystyrene, vinyl or polyester. In general, the substrate 17 is clear (that means transparent) or can be opaque, too. An opaque substrate 17 may comprise a transparent or translucent window at the active area 11. The window may be realized by inserting a transparent or translucent material or by reducing the thickness of the substrate 17. The substrate 17 is used to hold the porous layer 18, which may also be called membrane. Then, on one side or end of the membrane, the sample pad 14 is placed on the membrane, followed by the conjugate pad 15. On the other side or end of the membrane, the absorbent pad 16 is placed.

The test strip 10 may comprise at least one additional active area 12, 13 aligned with the pass-through or with an additional pass-through defined by the housing 20. In the shown example, the test strip 10 comprises two additional active areas 12, 13. For example, at least one of the additional active areas 21, 13 may be implemented as a control active area, e.g. as a control line. Thus, a change of the optical characteristics at the control active area indicates that the test is performed correctly, for example that a sufficient amount of liquid has been provided to the test strip 10. A result of the test may be detected by measurement of the optical characteristics at the active area 11. It is also possible that the additional active areas 12, 13 are provided to detect and measure additional analytes. In the shown embodiment each of the additional active areas 12, 13 are provided with an assigned to a respective additional pass-through . For example, the first additional active area 12 is aligned with a fourth opening 24 and fifth opening 25 forming the additional pass-through . Each additional pass- through is configured to provide an additional optical path from the top side of the housing 20 to the bottom side of the housing 20, i.e. through the housing 20. However, it is also possible that the active area 11 and the additional active areas 12, 13 are arranged at and aligned with a common pass- through, as shown in Fig. 3, for example. Further, the active area 11 and the additional active areas 12, 13 may be associated and aligned with a common light source 31 and/or a common photodetector 41. Alternatively, and as shown in Fig. 1, each additional active area 12, 13 may be associated with a respective additional light source 32, 33 and/or with a respective additional photodetector 42, 43.

The light source (s) 31 to 33 and the photodetector ( s ) 41 to 43 are not part of the test strip cassette 1, but are part of a monitoring device, as shown in Fig. 5. The light source (s) 31 to 33 may be arranged on a carrier 30 that is arranged parallel to the test strip 10. For example, the carrier 30 is implemented as printed circuit board, PCB . The photodetector ( s ) 41 to 43 may be arranged on a further carrier 40 that is arranged parallel to the test strip 10. For example, the further carrier 40 is implemented as PCB. The carrier 30 and the further carrier 40 comprise at least one electrical contact 35, 45, respectively. The electrical contacts may be called contact pads 35, 45. The carrier 30 and the further carrier 40 may be electrically interconnected by an electrical connection 50. The electrical connection 50 may be implemented as flex cable.

Fig. 2 shows another exemplary embodiment of the test strip cassette 1. The embodiment according to Fig. 2 is different from the embodiment according to Fig. 1 in that the test strip 10 is arranged differently inside the housing 20. In particular, the active area 11 is arranged on a side of the test strip 10 which, when the tests strip is inserted between the carrier 30 comprising the light source 31 and the further carrier 40 comprising the photodetector 41, faces the photodetector 41. This can mean that the active area faces the third opening 23 of the housing 20, while in the embodiment according to Fig. 1 the active area 11 faces the second opening 22. This means that in Fig. 1 the substrate 17 is arranged between the photodetector 41 and the active area 11 , while in Fig . 2 the substrate 17 is arranged between the light source 31 and the active area 11 . Further, compared to Fig . 1 , where the first opening 21 is arranged on the top of the housing 20 ( facing the carrier 30 ) , in Fig . 2 the first opening 21 of the housing 20 is arranged on the bottom of the housing 20 ( facing the further carrier 40 ) . The orientation shown in Fig . 2 can be reversed ( rotated 180 degrees ) so that the first opening 21 faces up when the test strip cassette 1 is inserted into a monitor device 100 .

Fig . 3 shows another embodiment of the test strip cassette 1 is a perspective cut-view through the test strip cassette 1 . In this example , the test strip 10 comprises the active areas 11 and one additional active area 12 , which may be implemented as control active area 12 .

It can be seen in Figure 3 that the housing 20 of the test strip cassette 1 comprises an inside surface , which comprises several alignment structures 26 forming slots , steps and/or protrusions . The alignment structures 26 are provided to receive the test strip 10 in a predetermined position and to provide positional alignment between the second opening 22 , the active areas 11 , 12 and the third opening 23 . In that way it is ensured that the test strip 10 has a fixed position with respect to the housing 20 . In all directions the test strip 10 cannot or can only slightly move inside the housing 20 , so that alignment with the pass-through is possible . Further, the alignment structures can also be configured to apply a force to one or more ends of the test strip 10 . In that way, a tension of the test strip 10 can be reali zed which may also be beneficial in view of alignment . This improves the accuracy of evaluating the respective measurement . Further, it is shown in Fig . 3 that the active area 11 and the additional active area 12 are aligned with a common pass-through . The housing 20 may consist of several parts that are assembled. For example, the housing 20, or parts of the housing 20, are made of an injection-molded material, e.g. plastic. For example, the housing 20 comprises a top part and a bottom part which enclose the test strip 10 when assembled, as shown in Fig. 3.

In Fig. 4 a further possible arrangement is shown in a crosssection. Some components of the test strip cassette 1 or the monitoring device 100, respectively, are omitted for ease of illustration. In the example according to Figure 4 the light source 31 is arranged on the carrier 30 outside the test strip cassette 1. Thus, the test strip cassette 1 does not comprise the light source 31. Figure 4 shows the second opening 22 defined by the housing 20 in more detail. It should be noted that the test strip cassette 1 may comprise more than openings that are designed in the same or a similar way. However, for ease of illustration only one second opening 2 assigned to active area 11 is shown. The second opening 22 tapers towards the active area 11 on the test strip 10. This means that a diameter of the second opening 22 is larger at an input side (where the light source 31 is arranged) and smaller at an output side (where the active area 11 is arranged) . As shown, the shape of the second opening 22 may be conical. This means that the second opening may have the shape of a truncated cone or frustum. In other words, a sidewall of the second opening 22 may define a surface shell of a truncated cone. However, different shapes, e.g. a parabolic shape, are also possible. Light rays from the light source 31 can be coupled into the second opening 22 under a wide angle. The light rays (indicated by arrows) are reflected at the sidewall of the second opening 22. Since the second opening 22 tapers towards the active area 11 the light rays are ef fectively collimated, so that an intensity of light at the active area 11 is increased . This ef fect can be enhanced, i f the sidewall is coated with a reflective layer 27 , as shown in Fig . 4 . The light hits the active area 11 from one side of the test strip 10 . At the other side of the test strip 10 the photodetector 41 is arranged (not shown) . The photodetector 41 detects a color change of the active area 11 , for example . Due to the advantageous design of the second opening 21 , the light intensity at the active area 11 can be increased . Thus , the requirements for a distance between the photodetector 41 and the active area 11 can be relaxed .

Fig . 5 shows an example of a monitoring device 100 that comprises the light source 31 and the photodetector 41 . The test strip cassette 1 as elucidated above can be inserted into the monitoring device 100 and can be removed again . The test strip cassette l is arranged between the carrier 30 with the light source 31 and the further carrier 40 with the photodetector 41 . In the shown example the carrier 30 is arranged above the test strip cassette 1 , while the further carrier 40 is arranged below the test strip cassette 1 . However, the arrangement can also be the other around . The monitoring device 100 may be named reader or PoC reader . The monitoring device 100 includes a device housing 101 . The light source 31 , the photodetector 41 and part of the test strip cassette 1 are located in the device housing 101 . In Figure 5 , the monitoring device 100 is only drawn schematically and as an example .

The monitoring device 100 may comprise guiding parts (not shown) to guide the test strip cassette 1 into the monitoring device 100 . The device housing 101 may include parts to provide a light shield which shields light from the external of the monitoring device 100 from penetrating into the interior of the device housing 101 .

Moreover, the monitoring device 100 comprises a control circuit 102 that is connected to the light source 31 and to the photodetector 41 . In particular, the control circuit 102 may be electrically connected to the electrical connection 50 that connects the carrier 30 with the light source 31 to the further carrier 40 with the photodetector 41 . The control circuit 102 is configured to detect whether the test strip cassette 1 is inserted or not and to provide an enable signal , when the test strip cassette 1 is inserted . In particular, the control circuit 102 may detect whether the test strip cassette 1 is inserted by means of a position sensor 108 to which the control circuit 102 is electrically connected as well . For example , the position sensor 108 measures i f the test strip cassette 1 is inserted correctly by determining a distance from the test strip cassette 1 to the position sensor 108 ( e . g . by optical means ) or by sensing a contact of the test strip cassette 1 with the position sensor 108 ( e . g . by mechanical means ) . However, the position sensor 108 can also be omitted and the correct insertion may also be detected by means of the light source 31 and the photodetector 41 serving as alternative position sensor .

Additionally, the monitoring device 100 may comprise an interface 104 connected to the control circuit 102 for providing information gained by the monitoring device 100 to an external device . The monitoring device 100 may also comprise a display 105 for displaying information gained by the control circuit 102 . For example , the display 105 may display the enable signal to indicate to a user that the sample liquid can be applied to the test strip 10 . Moreover, the display 105 displays the result of the test . The monitoring device 100 may comprise a power supply 106 such as a battery . Additionally, the monitoring device 100 may comprise a user interface 107 such as a button to start the measuring process .

The test strip cassette 1 may be configured to perform reactance measurements . To achieve proper measurements the monitoring device 100 may be equipped with a quali fied spectrometer photodetector integrated circuit .

Fig . 6 shows a perspective view on another exemplary embodiment of the monitoring device 100 having the test strip cassette 1 inserted . It shows the carrier 30 with three light sources 31 to 33 and the further carrier 40 with three photodetectors 41 to 43 inside the housing 101 of the monitoring device 100 . The carrier 30 and the further carrier 40 are electrically connected via a flex cable 50 . The test strip cassette 1 comprises the test strip 10 inside the housing 20 of the cassette 1 . The test strip cassette 1 defines three pass-throughs aligned with the respective lights sources 31 to 33 and the respective photodetectors 41 to 43 ( and with respective active areas of the test strip 10 ) . The test strip cassette 1 further comprises a collar which is accommodated in a receiving structure of the monitoring device housing 101 . Thus , the test strip cassette 1 can be properly aligned with the monitoring device 100 . The device housing 101 may consist of several parts that are assembled . For example , the device housing 101 , or parts of the device housing 101 , are made of an inj ection-molded material , e . g . plastics . The embodiments of the test strip cassette 1 , the monitoring device 100 and the method of producing the test strip cassette 1 disclosed herein have been discussed for the purpose of familiari zing the reader with novel aspects of the idea . Although preferred embodiments have been shown and described, many changes , modi fications , equivalents and substitutions of the disclosed concepts may be made by one having skill in the art without unnecessarily departing from the scope of the claims .

It will be appreciated that the disclosure is not limited to the disclosed embodiments and to what has been particularly shown and described hereinabove . Rather, features recited in separate dependent claims or in the description may advantageously be combined . Furthermore , the scope of the disclosure includes those variations and modi fications , which will be apparent to those skilled in the art and fall within the scope of the appended claims .

The term " comprising" , insofar it was used in the claims or in the description, does not exclude other elements or steps of a corresponding feature or procedure . In case that the terms " a" or " an" were used in conj unction with features , they do not exclude a plurality of such features . Moreover, any reference signs in the claims should not be construed as limiting the scope .

This patent application claims the priority of German patent application 102022117496 . 4 , the disclosure content of which is hereby incorporated by reference . References

I test strip cassette

10 test strip

I I active area

12 additional active area

13 second additional active area

14 sample pad

15 conj ugate pad

16 absorbing pad

17 substrate

18 porous layer

20 housing

21 first opening

22 second opening

23 third opening

24 fourth opening

25 fi fth opening

26 alignment structure

27 reflective layer

30 carrier

31 light source

32 additional light source

33 second additional light source

35 electrical contact

40 further carrier

41 photodetector

42 additional photodetector

43 second additional photodetector

45 electrical contact

50 electrical connection

100 monitoring device

101 device housing 102 control circuit

103 socket

104 interface

105 display 106 power supply

107 user interface

108 position sensor

Claims

1. Test strip cassette (1) , comprising

- a housing (20) defining a first opening (21) being configured to receive a sample liquid, the housing (21) further defining a second opening (22) and a third opening (23) which form a pass-through configured to provide an optical path through the housing (20) ,

- a test strip (10) arranged inside the housing (20) and comprising a sample pad (14) aligned with the first opening (21) and an active area (11) aligned with the pass -through,

- wherein the test strip (10) comprises at least one additional active area (12, 13) aligned with the pass- through or with an additional pass-through defined by the housing (20) , wherein the additional pass-through is configured to provide an additional optical path through the housing (20) .

2. Test strip cassette (1) according to claim 1, wherein the test strip (10) comprises a porous material, in particular nitrocellulose, which is configured to transfer the sample liquid from the sample pad (14) to the active area (11) , and wherein the active area (11) is provided with a chemical substance which reacts with a component of the sample liquid.

3. Test strip cassette (1) according to one of claims 1 to 2, wherein each additional active area (12, 13) is assigned to a respective additional pass-through .

Test strip cassette (1) according to one of claims 1 to 3, wherein at least one of the openings (22, 23) forming the pass-through defined by the housing (20) tapers towards the active area (11) of the test strip (10) .

5. Test strip cassette (1) according to one of claims 1 to 4, wherein a sidewall of at least one of the openings (22, 23) forming the pass-through defined by the housing (20) is coated with a reflective layer (27) .

6. Monitoring device (100) , comprising

- the test strip cassette (1) according to one of claims 1 to 5,

- a light source (31) ,

- at least one additional light source (32, 33)

- a photodetector (41) ,

- at least one additional photodetector (42, 43) , wherein

- the test strip cassette (1) is arranged between the light source (31) and the photodetector (41) , such that the pass-through defined by the housing (20) of the test strip cassette (1) and the active area (11) of the test strip (10) are aligned with the light source (31) and the photodetector (41) , and wherein

- the additional light source (32, 33) and the additional photodetector (42, 43) are assigned to the additional active area (12, 13) of the test strip (10) .

7. Monitoring device (100) according to claim 6, wherein the photodetector (41) and the additional photodetector (42) are configured to detect light in different wavelength regions.

8. Monitoring device (100) according to one of claims 6 to 7, wherein the monitoring device (100) is configured such that the test strip cassette (1) is selectively insertable into and removable from the monitoring device (100) .

9. Monitoring device (100) according to claim 8, further comprising a control circuit (102) , wherein the control circuit (102) is configured to detect whether the test strip cassette (1) is inserted or not and to provide an enable signal, when the test strip cassette (1) is inserted.

10. Monitoring device (100) according to one of claims 6 to 9, wherein the light source (31) is arranged on a carrier (30) , and the photodetector (41) is arranged on a further carrier (40) , the carrier (30) and the further carrier (40) being connected by an electrical connection (50) .

11. Monitoring device (100) according to one of claims 6 to

10, wherein the light source (31) and the photodetector (41) are synchronized.

12. Monitoring device (100) according to one of claims 6 to 11, wherein the active area (11) is arranged on a side of the test strip (10) which, when the test strip cassette (1) is inserted in the monitoring device (100) , faces the light source ( 31 ) .

13. Monitoring device (100) according to one of claims 6 to 11, wherein the active area (11) is arranged on a side of the test strip (10) which, when the test strip cassette (1) is inserted in the monitoring device (100) , faces the photodetector (41) .

14. Method for fabricating a test strip cassette (1) , comprising - providing a housing (20) defining a first opening (21) being configured to receive a sample liquid, the housing further defining a second opening (22) and a third opening (23) which form a pass-through configured to provide an optical path through the housing (20) ,

- providing a test strip (10) comprising a sample pad (14) , an active area (11) and at least one additional active area ( 12 , 13 ) ,

- assembling the housing (20) and the test strip (10) , such that the housing (20) encloses the test strip (10) and the sample pad (14) is aligned with the first opening (21) and the active area (11) is aligned with the pass-through, and wherein the at least one additional active area (12, 13) is aligned with the pass-through or with an additional pass-through defined by the housing (20) , wherein the additional pass-through is configured to provide an additional optical path through the housing (20) .