Patent Application
20240253030
The present disclosure relates to a rapid test device for detecting a target analyte in a saliva sample.
Lateral flow assays, LFA, or in other words lateral flow stripes are used to detect a target analyte without substantial lab equipment. LFAs are commonly operated in hospitals or clinical laboratories for qualitative detection of specific antigens in saliva samples. There is also a growing demand for using LFAs in home-based environment. Example target analytes reach from detecting fertility hormones, antigens of corona or flu viruses but are not restricted thereto.
LFAs typically include a plurality of pads coupled to each other which laterally transport a sample fluid along the pads and causing the sample fluid to perform selected biochemical reactions eventually indicating a positive or negative test result related to the presence or absence of the target analyte.
According to typical test settings known in the field, a swab is used to perform a throat swab for collecting saliva from the throat of the user. The collected saliva is then dipped into an extraction solution and mixed therewith. After a certain time, several drops of the mixture of the extract and the saliva are then inserted to a sample port located on top of the plastic test cassette to initiate the test process.
However, the process of throat swab, mixing, extracting and the step of inserting it into the receiving port requires several steps and involves certain waiting times even before initiating the actual test. The additional waiting times in the preparation are often failed since they are often not strictly followed.
Further, the swab and the extraction solution container are additional devices that are needed to perform the test. The LFA stripe is conventionally enclosed in plastic cassettes generally using acrylonitrile butadiene styrene, ABS, polystyrene, PS, or polypropylene, PP, as the basic material thereby consuming a large amount of plastic causing extensive plastic waste due to the increasing use for home-based testing.
There is a need to construe a rapid test device for detecting a target analyte in a saliva sample which can be operated more conveniently and efficiently while still ensuring testing integrity and sensitivity so that reliable results can be achieved as well as material saved. Further problems are solved as will be indicated in the below concrete description.
According to one aspect of the present disclosure, a rapid test device for detecting a target analyte in a saliva sample is provided. The rapid test device includes an elongate housing forming an interior channel extending in a flow direction. Further, a lateral flow test strip for detecting the target analyte is accommodated in the elongate housing and extends along the channel in flow direction, wherein the lateral flow test strip includes a sample pad to transport saliva along the lateral flow test strip in the flow direction. In addition, a saliva receiving port at an end portion of the elongate housing is configured to receive the saliva sample directly from a mouth of a user. A sample collection cavity extends from the saliva receiving port in the flow direction for collecting the saliva sample received through the saliva receiving port. The sample pad of the lateral flow test strip extends into the sample collection cavity to receive saliva collected in the sample collection cavity.
Further aspects of the present disclosure could be learned from the dependent claims or the following description.
Features will become apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which:
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. Effects and features of the exemplary embodiments, and implementation methods thereof will be described with reference to the accompanying drawings. In the drawings, like reference numerals denote like elements, and redundant descriptions are omitted. The present disclosure, however, may be embodied in various different forms, and should not be construed as being limited to only the illustrated embodiments herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those skilled in the art. In the drawings, the relative sizes of elements, layers, and regions may be exaggerated for clarity.
As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Further, the use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure.”. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
It will be further understood that the terms “include,” “comprise,” “including,” or “comprising” specify a property, a region, a fixed number, a step, a process, an element, a component, and a combination thereof but do not exclude other properties, regions, fixed numbers, steps, processes, elements, components, and combinations thereof.
Herein, the terms “upper” and “lower” are defined according to the z-axis. For example, the upper cover is positioned at the upper part of the z-axis, whereas the lower cover is positioned at the lower part thereof. In the drawings, the sizes of elements may be exaggerated for clarity. For example, in the drawings, the size or thickness of each element may be arbitrarily shown for illustrative purposes, and thus the embodiments of the present disclosure should not be construed as being limited thereto.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification, and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein.
According to one aspect of the present disclosure, a rapid test device for detecting a target analyte in a saliva sample is provided. The rapid test device includes an elongate housing forming a channel extending in the direction of flow. A lateral flow test strip to detect the target analyte is inserted in the elongate housing and is extending in the flow direction. The lateral flow test strip includes a sample pad. A saliva receiving port is disposed at an end portion of the elongate housing configured to receive the saliva sample from a mouth of the user. Further, the rapid test device includes a sample collection cavity extending from the saliva receiving port in the flow direction for collecting the saliva sample received through the saliva receiving port. The sample pad of the lateral flow test strip extends into the sample collection cavity.
Elongate implies that the housing has a longitudinal direction that is longer than wide. Furthermore, the lateral flow test strip may be in other words a lateral flow assay, LFA. Receiving the saliva from the mouth of the user may be referred as mouth collection, which means that the saliva sample is directly received from the user's mouth. That the sample pad extends into the sample collection cavity means in other words that a portion of the sample pad is located or exposed in the sample collection cavity. In other words, a portion of the sample pad is exposed to the sample collection cavity. In some embodiments, also a small portion of a conjugate pad may be exposed to the sample collection cavity.
The rapid test device provides convenient operating since the user can directly supply the saliva through the mouth via the saliva receiving port into the sample collection cavity. The sample collection cavity thus forms a reservoir to receive the saliva sample. Since the sample pad extends into the sample collection cavity, the saliva sample will contact the sample pad so that the test is initiated due to capillary transport through the sample pad. The rapid testing device works faster since less steps are required to perform the test. Such device better allows to perform the testing as part of a testing routine. In addition, fewer components are required when compared to using of a swab, applicator, liquid buffer etc.
According to an embodiment, the elongate housing may comprise at least one flow gate which protrudes inwardly into the channel toward the sample pad to reduce the area of the free space of the channel surrounding the sample pad. The flow gate acts as a flow resistance so that saliva cannot easily bypass the flow gate apart from being pulled through the sample pad by capillary action. The entering of saliva into the sample pad is thus improved so that subsequent pads receive the saliva through the sample pad. Thus, the flow gate protects from overflowing since a percentage of saliva properly entering the sample pad is increased and the amount of saliva that avoids entering the sample pad and the reaction zone of the conjugate pad is reduced. Therefore, the sensitivity of the test is improved since unreacted saliva cannot easily reach the membrane.
According to an embodiment, an inner top surface of the at least one flow gate may border with a top surface of the sample pad. In other words, the inner top surface is tight with the top surface of the sample pad. Thus, saliva that enters the space above the sample pad is forced to enter the sample pad and blocked from bypassing the flow gate at the top. Thus, sensitivity of the test result is improved since unreacted/unexposed saliva that has avoided the reaction zones in the conjugate pad is prevented from reaching test regions in the membrane of the lateral flow test strip diluting the test result.
According to an embodiment, at least one inner side surface of the at least one flow gate borders a corresponding side surface of the sample pad. In other words, the inner side surface is tight with the side surface of the sample pad. Thus, saliva that enters the space on the sides at the sample pad is forced to enter the sample pad and blocked from bypassing the flow gates at the sides. Thus, sensitivity of the test result is improved since unreacted/unexposed saliva that has avoided the reaction zones is prevented from reaching test regions of the lateral flow test strip, in particular conjugate pad and membrane.
In particular embodiments to improve the effect, both inner side surfaces and inner top surface of the at least one flow gate may border a corresponding surface of the sample pad.
According to an embodiment, the at least one flow gate borders the sample pad to be air permeable in the flow direction. Due to the air permeability, air that is inside the sample collection cavity and the channel can be evacuated when the user deposits or supplies saliva by mouth into the sample collection cavity to ease depositing of saliva through the mouth. In particular, in such embodiment, the user can receive perceptible feedback for when the sample collection cavity is full or filling up. Since saliva has a higher density than air and refers to a high viscosity fluid, it is relatively difficult for the saliva to pass through the flow gate outside of the sample pad of the lateral flow test strip. Therefore, a gentle resistance can be felt indicating the user an adequate amount of saliva.
According to an embodiment, a first flow gate among the at least one flow gate is located at end of the sample collection cavity opposite to the saliva receiving port. Thus, the first flow gate forms an end of the sample collection cavity and separates the sample collection cavity from the active biochemistry. Further, the flow gates thus help to directly feed saliva from the sample collection cavity into the sample pad.
According to an embodiment, a first and a second flow gate may be spaced apart from each other along the flow direction so to form an overflow cavity between the first and the second flow gate, wherein a venting hole may be formed in the upper portion of the overflow cavity between the first and the second flow gate. The overflow cavity may be in other words a venting chamber or ab overflow chamber. In an event that the user overcollects saliva so that the overflow cavity fills up, the venting hole may allow air to enter the overflow cavity to facilitate the drawing of saliva through the sample pad. In case of no venting hole, the movement of the saliva toward the further LFA strip pad components would be reduced or even prevented due to a low pressure generated inside such space between the flow gates. The venting hole has another effect in that if the user vastly overcollects saliva, the venting hole acts as a safety feature to prevent too much saliva from passing the second flow gate since excess saliva can escape through the venting hole thereby increasing the likelihood for a valid test result. Further, the venting hole also provides a user feedback that too much saliva was collected so that next time the amount of deposited saliva can be adjusted.
According to an embodiment, a surface area of the venting hole may be larger than an area of the free space of the channel surrounding the sample pad at the first and/or second flow gate. The surface area may be in other words a cross sectional area. This ensures that the ventilation hole offers a path of least resistance, thus venting excess saliva on top to protect the LFA component pads from a strong surge, which would otherwise flood the membrane or cause an overflow.
According to an embodiment, a third flow gate may be provided downstream of and spaced apart from the second flow gate. A third flow gate provides further redundancy to assure that the amount of saliva deposited into the sample pad is further increased and serves as a further measure for preventing overcollection of saliva.
According to an embodiment, the elongate housing may comprise an upper flow indication window positioned downstream from the at least one flow gate overlapping a conjugate pad of the lateral flow test strip. The flow indicator gives the user feedback that the test is functioning and starting due to flow indication due the reaction with the conjugate pad. This also provides information that no further saliva is required so that overcollecting can be avoided. Further, the user can still top-up the amount of saliva when no flow is detected through the flow indication window thus giving feedback to provide proper usage of the device.
According to an embodiment, the elongate housing may comprise a flat bottom sheet and a thermoformed thermoplastic top sheet coupled to the flat bottom sheet to form the elongate housing. Using thermoformed thermoplastic top sheet can reduce the amount of plastic by an order of magnitude, i.e., an amount of 70-90% of plastic can be saved compared to conventional plastic cassettes and the structures can be manufactured by hole punching in the thermoformed thermoplastic top sheet.
According to an embodiment, the thermoformed thermoplastic top sheet may include one among polyactide (PLA), polystyrene (PS), and polyethylene terephthalate (PET). Thus, using thermoformed thermoplastic top sheets implies that limitation to conventional polyethylene (PE), as being conventionally used can be overcome.
The thickness of the thermoformed thermoplastic top sheet may be 0.1 to 0.5 mm and preferably between 0.2 mm to 0.4 mm to 0.3 mm. Thus, the amount of plastic is reduced while still providing sufficient material strength.
According to an embodiment, the elongate housing may be injection molded. Such product can therefore be produced by 3D printing. Such product may meet current industry standards and may the production may be easily fitted into existing production schemes
According to an embodiment, a volume of the sample collection cavity is between 150 μl and 400 μl, preferably between 200 μl and 350 μl, more preferably between 250 μl and 300 μl. Such collecting volumes ensure sufficient saliva sample sizes for detecting the target analyte while preventing vast overcollection of saliva. Therefore, these volumes represent a sweet spot for collecting saliva directly from the mouth of the user.
According to an embodiment, a lateral flow test strip may comprise a cover tape on an absorption pad and a barcode printed on the cover tape, wherein the elongate housing comprises a barcode readout window which overlaps the printed barcode. Thus, a unique identifier can be provided to the rapid test device.
According to an embodiment, the lateral flow test strip may comprise a conjugate pad and a membrane, wherein a portion of the conjugate pad overlaps the membrane, and wherein the elongate housing comprises an inwardly extending contact protrusion protruding into the channel from an upper portion of the elongate housing to vertically contact the conjugate pad at a position where the conjugate pad overlaps the membrane. This ensures a stable contact between membrane and conjugate pad for providing persistent sample transfer across the pads.
According to an embodiment, a width of the saliva receiving port may be larger than a height of the saliva receiving port. A height may be for example less than 2.5 mm or more preferably less than 2 mm compared to common cassettes with a height of 4-5 mm. Such shape may better correspond to the mouth and may provide better delivery of saliva through the saliva receiving port. In addition, together with the saliva collecting cavity, a long, wide and flat geometry is provided. In this way, the surface tension created between the sample collection cavity walls and the high viscosity saliva sample is utilized, since it enables the saliva to cling inside the sample cavity with improved hygiene and handling of the saliva sample even if held upside down. This configuration ensures that no saliva leaks out of the saliva collecting port even if the rapid test device is held vertically upside down. If the sample collection cavity volume were distributed more evenly between width and height the saliva would readily slide out. Thus, this feature makes hygienic handling of the device possible despite of the lack of a collection pad or other intermediate medium for the sample to be deposited in.
In the following, a rapid testing device 1000 will be described according to
The rapid test device 1000 includes an elongate housing 10. The elongate housing 10 forms an inner channel which extends in a flow direction F. The flow direction F is a longitudinal direction of the housing 10 in which the elongate housing 10 is extending as indicated in the
A lateral flow test strip 20 for detecting the target analyte in the saliva sample is accommodated inside of the elongate housing 10. In particular, the lateral test strip 20 is held inside the channel of the elongate housing 10 and aligned to extend in the flow direction F. An example lateral flow test strip 20 disposed inside the elongate housing 10 is disclosed in the exploded view of
The lateral flow test strip 20 includes a sample pad 22. The sample pad 22, when receiving saliva, can transfer the received saliva in flow direction F due to capillary transport. That is, the sample pad 22 can transport the saliva toward successive component pads of the lateral flow test strip 20. The sample pad 22 may include for example a fiber material like cellulose. Functional additives may be deposited in the sample pad 22, for example, to improve the flow transport properties of the saliva and/or to be robust to saliva property fluctuations like viscosity.
The lateral flow test strip 20 may comprise several further functional pads which can be partially overlapped to provide interfaces that allow an effective flow of saliva in the flow direction F and which allow for biochemical reactions of specifically deposited molecules with the target analyte in the saliva. They can also comprise fibers like cellulose or other porous materials to facilitate capillary flow. For example, as shown in
The rapid test device 1000 includes a saliva receiving port 30. The saliva receiving port 30 is formed at an end portion of the elongate housing 10. This offers an interaction very similar to a whistle which is very intuitive to most. In particular, first-time users can rapidly learn the sample collection as the mental model will already be there and the interaction with the rapid test device 1000 can be communicated with simple diagrams or words in comparison to a cumbersome folding design. The saliva receiving port 30 can be taken into the mouth of the user and/or partially inserted into the mouth so that saliva can be directly fed into the rapid test device 1000 through the saliva receiving port 30. For example, to better match with the mouth shape of humans, the width of the saliva receiving port 30 may be larger than the height of the saliva receiving port 30 as disclosed for example in
A sample collection cavity 40 is provided which extends from the saliva receiving port 30 in the flow direction F. The sample collection cavity 40 allows to collect, i.e., to store, an amount of saliva that is received through the saliva receiving port 30. The saliva receiving port 30 is configured so that saliva can be directly supplied from the mouth of the user to the rapid test device 1000. A suitable volume of the sample collection cavity 40 may be between 150 μl and 400 μl, preferably between 200 μl and 350 μl, more preferably between 250 μl and 300 μl. These predetermined volumes can be set to limit a suitable amount of saliva, for example specific to a target analyte, that can be processed by the lateral flow test strip 20 and to provide reliable results.
A part of the sample pad 22 of the lateral flow test strip 20 is exposed in the sample collection cavity 40. In particular, this part of the sample pad 22 extends into the sample collection cavity 40 as being illustrated for example in
To provide an improved sensitivity, e.g., reducing false negatives, of the saliva testing and to increase robustness against incorrect use or misuse as well as ensuring successful outcome for a higher percentage of tests administered, several constructive measures may be integrated which are explained in the following. In particular, the elongate housing 10 may comprise at least one flow gate 50, 60, 70 positioned at the end and/or downstream from the sample collection cavity 40. The at least one flow gate 50, 60, 70 is located above the sample pad 22, i.e., at a designated position of or with respect to the sample pad 22. In the specific example as shown in
In geometric terms, the at least one flow gate 50, 60, 70 protrudes inwardly into the channel toward the sample pad 22. Thereby the flow gate 50, 60, 70 reduces the free area 52 of the channel surrounding the sample pad 22. This feature will be described in more detail with respect to
As can be seen in
Referring to
According to
In more different words, the outer surface of the sample pad 22 fits or corresponds geometrically with the inner surface of the flow gate 50. Thereby, the flow gate 50 forces the saliva to enter the sample pad 22 and to provide resistance for penetrating the flow gate 50 without entering the sample pad 22. Thus, the constriction reduces the free surrounding free area 52 of the sample pad 22 to reduce the amount of free bypassing saliva which may dilute the test result.
Further, the flow gate 50 borders the sample pad 22 to be air permeable in the flow direction F. This can for example be seen in
Referring back to
A cross section of the overflow cavity 80 is disclosed in
The overflow cavity 80 offers an additional volume into which excess saliva can fill. Without it, i.e., if the channel is entirely narrow, the overflow would rapidly shoot along the length of the lateral flow strip 20.
Since due to the venting hole 82 air can be exchanged, the venting hole 82 supports that saliva is sufficiently drawn into and through the sample pad 22. In addition, it protects the testing integrity from too much saliva since excess saliva building up in the overflow cavity 80 may exit through the venting hole 82 to increase the testing integrity in case of overcollection. Further, the user receives adjustive feedback of having overcollected saliva so that in consecutive uses less saliva should be supplied.
The surface area 84, or in other words section area, can have predetermined size. In particular, the surface area 84 of the venting hole 82 can be set to be larger than the free area 52 of the space of the channel surrounding the sample pad 22 at the first and/or second flow gate 50, 60. This facilitates that the venting hole 82 becomes a path of least resistance compared to the flow gates 50, 60 so minimize transfer of saliva in case of overcollection that potentially floods the membrane and thus would dilute the test result.
Referring back to
To provide further control feedback to the user, the following measures can be integrated as shown in
Furthermore, a portion of the conjugate pad 24 may overlap with the membrane 26 as can be seen in
In addition, a second inwardly extending protrusion 130 may be provided to exert pressure on the absorption pad 28 and the membrane 26 at a location where the membrane 26 and the absorption pad 28 overlap each other. This is for example disclosed in the cross section of
To support the inserted lateral flow test strip 20, an end wall 140 is provided at an end of the opposite to the saliva collection port 30. A test readout window 100 is included which allows the user to interpret the test results according to the color indication at a c line 104 and a t line 102, for example. In other embodiments, an LFA reader may be used to interpret the results. The test device 1000 is not restricted to colorimetric reading of the lateral flow test strip 20 but fluorescence or other detection methods could be used.
The lateral flow test strip 20 may comprise a cover tape 112 on the absorption pad 28 of the lateral flow test strip 20. A barcode 114 may be printed on the cover tape 112. In correspondence, the elongate housing 10 comprises a barcode readout window 110 which overlaps the printed barcode 114. In this manner, a unique identifier of the rapid test device 1000 can be provided and suitably integrated in the rapid test device 1000.
The above described features can be accompanied with a reduction of weight and reduction of amount of plastic as described in the following. As shown in the exploded view in
When using thermoformed thermoplastic, the amount of plastic can be reduced compared to commonly known cassettes. In particular, polypropylene can be avoided and instead, for example, biodegradable materials used. Preferred materials for the thermoplastics include polyactide (PLA), polystyrene (PS), and polyethylene terephthalate (PET). A thickness of 0.1 to 0.5 mm and preferably between 0.2 mm to 0.4 mm may be applied.
In this embodiment, the elongate housing 10 is injection molded. Thus, the elongate housing 10 including the lateral flow test strip 20 can be produced by using 3D printing. Such product can be readily produced by current production schemes.
In this embodiment, three flow gates 50, 60, 70 are provided to protect form overcollecting and to facilitate drawing saliva into the sample pad 22. Three flow gates 50, 60, 70 can also be applied to the first embodiment.
In summary, the presented embodiments disclose a rapid test device 1000 for detecting a target analyte in a saliva sample which are more conveniently and efficiently operated. Due to additional measures as described above, reliable testing results can be achieved by controlling the saliva flow as well as material saving.
The reference identifiers used above are defined as follows:
| Number | Date | Country | Kind |
|---|---|---|---|
| 23153658.2 | Jan 2023 | EP | regional |
