The invention relates to the field of lateral flow assay devices. Lateral flow assay devices are widely used for in vitro diagnosis of various biological samples. Known examples are pregnancy tests, malaria tests, HIV tests and tests for a coronavirus, particularly SARS-CoV-2. In general lateral flow assay devices are useful for quickly and/or accurately detecting the presence or absence of a predetermined test compound, including cells, antigens, and drug compounds and their metabolites in a sample. Known lateral flow assay devices to this end utilize a diagnostic test strip, usually a paper strip made of cellulose, comprising indicator means for the predetermined test compound and the test strip contained in a cassette that serves to protect the test strip and maintain the test strip in intact form prior to use. Most of the available lateral flow assay devices have the cassette made from plastics which allows for a quick and relative easy low cost production. However with the very high number of lateral flow assay tests being produced and sold each year globally these plastic cassettes form an undesirable amount of non-recyclable plastic waste. This is even more of a problem in view of the demand for point of care testing growing each year. As a consequence lateral flow assay devices have been developed that comprise a biodegradable cassette. A known example is a lateral flow assay device with a diagnostic test strip inserted into a cassette made of cellulose material.

Although the known biodegradable lateral flow assay device offers a more environmental friendly solution as compared to the available plastic examples, there is a further need for an improved lateral flow assay device.

In accordance it is an aim to provide an improved biodegradable lateral flow assay device. In particular it is an aim to provide a biodegradable lateral flow assay device that is reliable and/or convenient to produce. Another aim is to provide an improved lateral flow assay kit, in particular an improved lateral low assay kit comprising in addition to an improved biodegradable lateral flow assay device one or more biodegradable kit parts such as a biodegradable swab and/or a biodegradable buffer liquid container.

Accordingly, in an aspect herein there is provided a lateral flow assay device for in vitro diagnostics of a biological sample comprising a diagnostic test strip inserted into a cassette, the cassette comprising a lower cassette part and an opposite upper cassette part coupled to each other and defining a test chamber there between containing the diagnostic test strip, wherein the cassette is made of a biodegradable material and wherein at least one of the lower cassette part and upper cassette part is made of 3D printable curable material. The at least one of the lower cassette part and upper cassette part of the cassette made from a biodegradable and 3D printable curable material enables a convenient production of the lateral flow assay device using 3D printing while being environmental friendly in view of the biodegradability of the cassette. Preferably the 3D printable curable material is curable from a liquid phase into a solid phase relatively easily without requiring elaborate and/or costly processes. Optionally, the 3D printable curable material can be cured from a liquid phase into a solid phase by changing the temperature of the 3D printable curable material and/or by drying the 3D printable curable material. Optionally the 3D printable curable material is provided in a liquid phase, i.e. as a liquid, for 3D printing of the 3D printable curable material and is dried by exposure to air after printing to provide the 3D printable curable material in cured form to make the at least one of the lower cassette part and upper cassette part of the lateral flow assay device in solid and durable useable form. Preferably the 3D printable curable material is cured by exposure to air at room temperature, i.e. approximately between 17-22 degrees Celsius.

For a further improvement in ease of production of the lateral flow assay device one of the lower cassette part and upper cassette part of the cassette is formed as an at least substantially flat cover plate that covers one side of the test chamber. The other of the lower cassette part and upper cassette part of the cassette may be formed with a base wall defining an opposite side of the test chamber and with a side wall extending between the base wall and the cover plate around the test chamber. Optionally the base wall and/or side wall comprises at least one opening to enable access to the test chamber from outside the cassette. For example the at least one opening may be an opening through which a biological sample such as a saliva sample can be brought into the test chamber for interaction with the diagnostic test strip. The at least one opening may alternatively or additionally be an opening for inserting the diagnostic test strip or a replacement diagnostic test strip in the test chamber. The at least one opening may also alternatively or additionally be an opening such as a window for visual inspection of at least part of the test chamber. Preferably the base wall and/or side wall comprises a first opening through which a biological sample can be brought into the test chamber and a second separate opening for visual inspection of at least part of the test chamber.

Optionally the lower cassette part and upper cassette part are made of different materials. However the lower cassette part and upper cassette part may also be of the same material. In an aspect the lateral flow assay device has the lower cassette part and the upper cassette part made of 3D printable curable material. Preferably the 3D printable curable material is gelatin or a biodegradable gelatin composition. Gelatin is a soluble protein obtained by the partial hydrolysis of collagen derived from the bones, hides and skins of animals such as cows, pigs and fishes. Gelatin is widely used in healthcare and medicine, for example in pill capsules, vaccines and hemostats. The gelatin or gelatin composition may be adapted to be solid at and below normal use temperatures, e.g. below 30 degrees Celsius, and to liquefy when exposed to an increased temperature, e.g. above 40 degrees Celsius such that it can be easily printed in liquefied form and be cured by drying to ambient air at normal use temperatures such as at room temperature. Preferably a gelatin composition is used which is adapted to have a hydrophobicity suitable for normal use of the lateral flow assay device. In particular the gelatin composition renders, when cured, the at least one of the lower cassette part and upper cassette part of the cassette to maintain its form and usability for supporting the diagnostic test strip when exposed under normal conditions to a liquid, e.g. a liquid biological sample.

Therefore, a lateral flow assay device for in vitro diagnostics of a biological sample comprising a diagnostic test strip inserted into a cassette, the cassette comprising a lower cassette part and an opposite upper cassette part coupled to each other and defining a test chamber there between containing the diagnostic test strip, wherein the cassette is made of a biodegradable material and wherein at least one of the lower cassette part and upper cassette part is made of 3D printable curable material, wherein the 3D printable material is gelatin or a gelatin based biodegradable material, is preferred.

Thus, a lateral flow assay device, wherein the lower cassette part and the upper cassette part are made of the same 3D printable gelatin or a gelatin based biodegradable material, is preferred.

The cassette can optionally be conveniently formed with a production process in which a warmed sheet of plain plasticized gelatin is placed over a die plate having a number of depression or moulds or numerous die pockets that enable forming the other of the lower cassette part and upper cassette part of the cassette with a base wall and with a side wall. For example by applying vacuum, the warmed sheet is drawn into these depressions or pockets to form corresponding cassette parts. A second sheet of gelatin is carefully placed on top of the formed cassette parts to enable forming of the at least substantially flat cover plate of the cassette. Pressure is then applied by a top plate of the mould to form and seal the cassettes, and the cassettes are cut into individual units. The 3D printable curable material may alternatively be a plantbased 3D printable curable material. Preferably the plant-based material is a biodegradable grain-based composition. The biodegradable grain-based composition optionally comprises a wheat flour, preferably a fine or milled flour such as a milled flour from Triticum durum wheat, i.e. Semolina. Plant-based materials are environmental friendly both in use, i.e. have very good biodegradability, and in production. Grain-based materials are moreover available in large quantities and inexpensive, enabling production of low cost cassette parts of the lateral flow assay device. A grain-based composition comprising in particular a wheat flour, preferably a fine or milled flour, provides good 3D printing properties with easy curing after printing, enabling the production of a solid and durable cassette part. Optionally, the lateral flow assay device has at least one of the lower cassette part and upper cassette part 3D printed in one piece. Preferably at least the other of the lower cassette part and upper cassette part with base wall and side wall is 3D printed. The lower cassette part and the upper cassette part may each be 3D printed in one piece. The one of the lower cassette part and upper cassette part of the cassette, particularly when formed as an at least substantially flat cover plate, may also be made in another way, such as using a molding technique.

In an aspect of the lateral flow assay device the lower cassette part and the upper cassette part are coupled to each other with a manually releasable connection. The lower cassette part and upper cassette part can accordingly be manually released from each other to enable inspection of the test chamber and/or to exchange the diagnostic test strip for a replacement diagnostic test strip if desired. For instance the manually releasable connection can be realized with unlockable snap -fit connection means that may be 3D printed integrally with at least one of the lower cassette part and upper cassette part. In another aspect herein there is provided a lateral flow assay kit comprising a lateral flow assay device as described herein and at least one of the group consisting of a replacement diagnostic test strip, a sample taker such as a swab, a sample holder such as a tube, and a waste container such as a zip-lock bag. Preferably, in addition to the lateral flow assay device also the at least one of the group consisting of a replacement diagnostic test strip, a sample taker such as a swab, a sample holder such as a tube, and a waste container such as a zip-lock bag is biodegradable and/or made of 3D printable curable material.

These and other objects and aspects are hereinafter further elucidated by the appended drawing and the corresponding embodiment, which forms part of the present application. The drawing is not in any way meant to reflect a limitation of the scope of the invention, unless this is clearly and explicitly indicated. In the drawing:

Fig. 1 shows an exploded view of an embodiment of a lateral flow assay device in accordance with a first aspect herein.

The description of the embodiment is not limited to the example shown in the figure and the reference numbers used in the detailed description and the claims are not intended to limit the description of the embodiment, but are included to elucidate the embodiment by referring to the example shown in the figure.

In the embodiment as shown in figure 1, the lateral flow assay device 1 for in vitro diagnostics of a biological sample comprises a diagnostic test strip 2 inserted into a cassette, the cassette comprising a lower cassette part 3 and an opposite upper cassette part 4. The lower cassette part 3 and the opposite upper cassette part 4 are coupled to each other and define a test chamber containing the diagnostic test strip 2. The upper cassette part 4 is formed as an at least substantially flat cover plate that covers one side of the test chamber. The upper cassette part 4 has an opening 5 that forms an entrance through which a biological sample can be brought into the test chamber for interaction with the diagnostic test strip 2. The upper cassette part 4 is transparent at least in part in order for a user to be able to view at least a part of the diagnostic test strip 2 that has the indicator means for the predetermined test compound of the lateral flow assay device without having to open the lateral flow assay device.

The lower cassette part 3 is formed with a base wall 6 defining an opposite side of the test chamber and with a side wall 7 extending between the base wall 6 and the upper cassette part 4 around the test chamber. The lower cassette part 3 has on the base wall 6 support means 8 for supporting the diagnostic test strip 2 at a distance above the base wall 6 in a correct position for reliable interaction in use with a biological sample.

The lower cassette part 3 is 3D printed in one piece using a gelatin composition. The upper cassette part 4 is also 3D printed in one piece using the same gelatin composition. The gelatin composition is adapted to be solid at normal use temperatures and conditions, such that after printing and cooling to approximately room temperature of the test cassette parts the cassette is solid and durable for use. The gelatin composition is further adapted to have a transparency in solid form that enables the user to visually inspect the test chamber through the upper cassette part. The gelatin composition is fully biodegradable, so that the lateral flow assay device is plastic free and environmental friendly.

While the current application may describe features as part of the same embodiment or as parts of separate embodiments, the scope of the present invention also includes embodiments comprising any combination of all or some of the features described herein.