WO2010109445A1

WO2010109445A1 - Assay device and method

Info

Publication number: WO2010109445A1
Application number: PCT/IL2010/000192
Authority: WO
Inventors: Nir Sterer; Melvyn Rosenberg-Nevo
Original assignee: Ramot At Tel-Aviv University Ltd.
Priority date: 2009-03-23
Filing date: 2010-03-09
Publication date: 2010-09-30

Abstract

An assay device for detection of at least one analyte in a sample, the device comprising a housing and a carriage displaceable with respect to one another and comprising at least one sample assay array. One of the housing and the carriage comprises a sample receiving well and the other of the housing and the carriage comprises a sample introducing opening and a reagent agent location holding a reagent agent. The device further comprises at least two operative positions: a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location.

Description

ASSAY DEVICE AND METHOD

FIELD OF THE INVENTION

This invention relates to a simple and compact, disposable assay protective device and a method for using same for detection of an analyte or determining its concentration in a sample.

BACKGROUND OF THE INVENTION

Biological and chemical reaction devices have already been proposed, with the aim of simplifying the work of laboratories and individuals, and preventing the risks of contamination and inaccurate assaying. for example, WO9313856 discloses an assay apparatus comprises a first assay zone constituted by a foam pad on a first solid support component constituted by a plastics card having a channel on one face thereof bordered by undercut walls receiving a plastics slide as a second solid support component having as a second assay zone a window. The support components fit together for relative sliding movement such that said zones are slidable with respect to one another from a first position in which said zones are separated from one another to a position in which said zones are brought into mutual contact by sliding motion. An antibody may be bound to the foam pad. An enzyme antibody conjugate may be unbound on the pad. An assay reagent which takes part in an observable reaction with the conjugate or a species to be assayed is present beneath window.

A different arrangement is disclosed in US patent 4,769,333 directed to a personal, disposable hand held diagnostic kit having a specimen support member such as a membrane, wafer or the like including a plurality of liquid receptacles with means for applying the liquids to said support member in sequence for relatively immediate observation of reaction and ultimate diagnosis. SUMMARY OF THE INVENTION

The present invention is concerned with a simple to use and fool-safe safe assay device. The device is configures as a disposable and substantially cheep device, yet safe in operation, i.e. with no or substantially little risk of contamination.

According to the present invention there is provided an assay device for detection of at least one analyte in a sample, the device comprising a housing and a carriage displaceable with respect to one another and comprising at least one sample assay array, wherein one of said housing and said carriage comprises a sample receiving well and the other of said housing and said carriage comprises a sample introducing opening and a reagent agent location holding a reagent agent; the device comprising at least two operative positions: a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location.

According to one particular example, the device comprises three operative positions: an initial, closed position wherein each of the sample receiving well and the reagent agent location is sealingly concealed, a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location.

According to another of its aspects the invention there is concerned with an assay method for detection of an analyte or determining its concentration in a sample, the method comnmprising:

(a) obtaining an assay device comprising a housing and a carriage displaceable with respect to one another and comprising at least one sample assay array, wherein one of said housing and said carriage comprises a sample receiving well and the other of said housing and said carriage comprises a sample introducing opening and a reagent agent location holding a reagent agent; the device comprising at least two operative positions: a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and a assay position wherein the sample receiving well coincides with the reagent agent location;

(b) introducing the sample through the sample introducing opening into the sample receiving well; (c) manipulating the device into the assay position for reaction to take place between the sample and the reagent agent;

(d) observing the result of the interaction between sample and reagent agent. According to a modification, the device comprises three operative positions: an initial, closed position wherein each of the sample receiving well and the reagent agent location is sealingly concealed, a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location. In this case the method comprises a further step before step (b) above, namely manipulating the device into the sample introducing position.

Where the device comprises at least two sample assay arrays and wherein steps b) to e) are carried out for each of the sample assay arrays

Any one or more of the following configurations and examples may be used in accordance with modifications of the invention:

• each sample assay array comprises at least one of a separate sample receiving well and a reagent agent location.

• two or more sample assay arrays share at least one of sample receiving well and a reagent agent location.

• the housing and the carriage are rotatably slidable, wherein the sample receiving well, the sample introducing opening and the reagent agent location of a sample assay array are equi-radially disposed.

• two or more equi-radially disposed sample assay arrays arte provided, wherein rotation of one of the housing and the carriage in one direction manipulates a first sample assay array and rotation in an opposite direction manipulates a second sample assay array.

• two or more sample assay arrays are provided, each of which disposed about a diverse radii.

• the housing and the carriage are coaxial cylinders rotatably slidable, wherein the sample receiving well, the sample introducing opening and the reagent agent location of a sample assay array are equi-axially disposed in the housing and carriage.

• the housing and the carriage are linearly slidable, wherein the sample receiving well, the sample introducing opening and the reagent agent location of a sample assay array are linearly disposed. • the device comprises at least two sample assay arrays parallely disposed along the housing and carriage.

• one of the housing and the carriage is formed with longitudinal slots for sliding engagement with the other of housing and carriage.

• a locking arrangement is provided such that the carriage is displaced with respect to the housing between three distinct positions.

• the locking arrangement is a one-way displacing ratchet mechanism.

• a see-through window is provided over the reagent agent location.

• the see-through window is covered by a removable light shield so as to prevent exposure of the reagent agent to light prior to use.

• the carriage does not project from the housing at any of the three positions.

• the reagent agent location remains unexposed at any of the three positions.

• the sample receiving well is unexposed at the initial, closed position.

• a visual indicator is provided to indicate a respective position of the device.

• the reagent agent is suited for detecting conditions of oral malodor.

• a motion restricting arrangement is provided for restricting displacement of the carriage and housing between only said three operative positions. According to a particular design, the motion restricting arrangement comprises a projection from a surface of one of the housing and carriage slidingly received within a groove formed in a flush mating surface of the other of said housing and carriage.

The device of the present invention may be utilized for detecting in a sample of human or animal origin the presence or absence of a single or multiple analyte. In order to detect and/or analyze various bodily fluids such as saliva, blood, urine, semen, feces, vaginal secretion and other, the device is provided with a reagent membrane provided at the reagent agent location. Such a membrane may contain for example a dry chemistry reagent mixture, that is, a mixture in which the wet chemistries are imbibed into an absorbent or bibulous medium, dried, and later reconstituted by fluid from the test sample. A transparent, see-through layer is provided over the reagent membrane facilitating any changes in color or texture.

The indicating reagent mixture must be capable of detecting the presence of an analyte in a sample. The mixture may comprise for example various reagents and/or assays for detecting the analyte and an indicator, both impregnated in the membrane matrix forming the reagent layer.

A portion of the reagent membrane may further be provided with a control substance to act as a quality control material to check that the device is functioning correctly. According to another example, the reagent membrane may be a multi-analyte detection system such that the membrane is divided to several section each of which is impregnated with a different reagent and/or indicator.

According to one example the indicator changes color, depending on the presence or concentration of a particular analyte in a biological sample applied to the membrane. The reaction on the membrane may for example be read visually by reference to a color standard or colorimetrically by instrument calibrated or programmed to detect a certain color.

Different reagents may be used to determine the content of the sample and/or analyte The reagent layer may be impregnated with an assay for detecting helicobacteria, volatile sulfur compounds (VSCs), such as hydrogen sulfide, methyl mercaptan, dimethyl disulfide, and dimethyl sulfide, polyamines, such as putrescine and cadaverine associated with halitosis and present in a saliva; rates of electrolytes, enzymes, various bacteria species present in a saliva; hormones, protein, ketones, albumin or glucose in urine; such membrane may also be used to test for cholesterol, triglycerides, calcium or albumin in whole blood and may be used to detect for example presence of semen, saliva, blood, urine, perspiration, vaginal secretion an other body fluids in a sample.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, examples will now be described, by way of several non-limiting examples only, with reference to the accompanying drawings, in which:

Figs. IA to 1C illustrate an assay device according to a fist configuration of the present invention at its closed position, sample introducing and assay position, respectively;

Figs. 2A and 2B are front and rear respective isometric views of the device seen in Figs. 1 ; Fig. 2C is an exploded isometric view of the device seen in Figs. 1 ;

Figs. 3 A to 3C are schematic longitudinal sections along lines III-III in Figs. IA to 1C, respectively;

Figs. 4A to 4C illustrate an assay device according to a second configuration of the present invention, at its closed position, sample introducing and assay position, respectively;

Figs. 5A; 5B, 6A; 6B and 7A; 7B are schematic sectioned views taken along lines I-I and H-II

Fig. 8 is a schematic top view of an assay device according to a third configuration of the invention, at its closed position;

Figs. 9 A and 9B are schematic top views of the device of Fig. 8 at a first sample introducing and first assay position, respectively;

Figs. 1OA and 1OB are schematic top views of the device of Fig. 8 at a second sample introducing and second assay position, respectively;

Figs. HA to HC illustrate an assay device according to a fourth configuration of the present invention, at its closed position, sample introducing and assay position, respectively;

Figs 12A to 12C illustrate an assay device according to a fifth configuration of the present invention, at its closed position, sample introducing and assay position, respectively; and

Figs. 13A and 13B are exploded isometric views of assay devices according to yet other examples of the present invention.

DETAILED DESCRIPTION OF EXAMPLES

Attention is first directed to Figs. 1-3 directed to an assay device in accordance with a first example of the present invention generally designated 10 composed two principle elements, namely a housing 12 and a carriage 14 axially slidingly displaceable with respect to one another as can be appreciated from Figs. IA - 1C and the respective side schematic illustrations disclosed in Figs. 3 A-3C.

The housing 10 is formed with a sample-introducing opening 16 and a reagent agent location 18 in the form of a depression fitted with a reagent agent as will be discussed hereinafter in farther detail. The reagent agent location is fitted with a see- through window 20 (best seen in figs. 3A-3C).

The carriage 14 is fitted with a sample-receiving well 22 in the form of a cavity, the arrangement being such that said sample-introducing opening 16, reagent agent location 18 and sample-receiving well constitute together a sample assembly array coaxially aligned as can best seen in Figs. 1A-1C.

The housing 12 is longer than the carriage 14 and is formed at its distal end with a plurality of radially inwardly projecting saw-like teeth projecting towards one another at both sides of the housing 12 whilst the carriage 14 is fitted with an inverted set of saw-like teeth 28 radially projecting outwardly whereby the housing 12 and the carriage 14 are slidingly displaceable with respect to one another in one direction only, as exemplified in Figs. IA- 1C, between three distinct positions namely, an initial, closed position (Figs. IA and 3A), a sample-introducing position (Figs. IB and 3B) and an assay position (Figs. 1C and 3C).

As seen, at the closed position the opening 16 extends intermediate the reagent agent location 18 and the sample-receiving well 22, whilst the two latter are sealingly concealed namely unexposed to any sort of contamination. Upon sliding displacement of the carriage 14 in direction of arrow 30 the sample-receiving well 22 co-extends below the sample-introducing opening 16, allowing for introducing of a sample into the well 22 through the opening 16. Upon further displacement of the carriage 14 in direction of arrow 32 the sample-receiving well 22 now co-extends with the reagent agent location 18 whereby the sample contained within the sample-receiving well 18 comes into contact with the reagent provided at the reagent agent location 18.

Depending on the type of assay performed, the reagent contained within the reagent agent location 18 will change its color to be viewed through the see-through window 20, indicative of an analyte in the sample.

The device is a disposable device, not intended for secondary use. Even more so, the arrangement is such that the pair of housing 12 and carriage 14 are not detachable from one another (i.e. the carriage 14 is slidably displaceable only between its three distinct positions disclosed above, wherein detachment of the carriage 14 from the housing 12 is prevented, e.g. by means of an upwardly projecting pin 34 projecting from an upper surface 36 of carriage 14, said pin being slideably displaceable within a longitudinal groove 40 formed in housing 12, thus preventing this assembly or exposure of the sample/reagent agent, so as to minimize risk of hazardous or environmental contamination). It is also noticed that the carriage 14 is slideable between the three distinct positions mentioned above, however it never projects between either end of the housing 12.

In some cases the reagent agent may be sensitive to light and for that purpose a see-through window is covered by a removable light shield so as to prevent exposure of the reagent agent to light prior to use. The removable light shield according to one example is a removable sticker and according to another example is a sliding cover displaceable over the top surface Of the housing between a concealing position in which the window is covered and will thus prevent light from reaching the reagent agent, and an open position in which the window is exposed for visualizing the reagent agent. Alternatively, the see-through window is formed at carriage at the bottom surface of the sample-receiving well, such that the reagent agent is exposed only once the carriage is displaced into the assay position.

Whilst the device and method referred to in connection with figures 1 to 3 make reference to a device manipulable between three operative positions, it is realized that other examples are possible with a device manipulable between only two operative positions, namely a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location. Thus, the device lacks the first operative position in which the sample receiving well is sealingly concealed. This applies also to the remaining examples as discussed herein after in connection with figures 4 tol 3.

Turning now to Figs. 4-7 there is illustrated a second example of an assay device in accordance with the present invention generally designated 50 and composed of a disk-like housing 52 and disk-like house 54 coaxially pivoted about a rotation axis A, the two discs having flushing surfaces. The arrangement is such that a single sample array is provided, wherein the housing 52 is formed with a reagent agent location 56 sealingly covered with a see-through 57 (best seen in Figs. 5A, 6A and 7A), and a sample introducing opening 58 (Figs. 5B, 6B and 7B). Likewise the previous example, carriage 54 is fitted with a sample receiving well 58 (seen in Figs. 5A, 6B and 7A, and superimposed in Figs. 4A-4C, illustrated by dashed lines for sake of clarity). The arrangement is such that a top surface 66 of the carriage 54 bear flush against a bottom surface 68 of the housing 52 in a slidelingly rotatable about the common axis of rotation A, wherein the reagent agent location 56 the sample introducing opening 58 and the sample receiving well 62 co-axially radially extend and are substantially equal size such that the sample receiving well 62 is displaceable between the three distinct positions namely an initial, closed position wherein the sample receiving well 62 and the reagent agent location 56 are sealingly concealed (Figs. 4A, 5A and 5B), a second, sample introducing position wherein the sample receiving well 62 coincides with the sample introducing opening 58 (Figs. 4B, 6A and 6B) and a third, assay position, wherein the sample receiving well 62 coincides with the reagent agent location 56 (Figs. 4C, 7A and 7B).

It is appreciated that in the examples of Figs. 4-7 the carriage 54 is displaceable in direction of arrow 72 (Figs. 4A and 4B between the three distinct positions as disclosed above).

The carriage 54 is designed for uni-directional rotation (in a counterclockwise direction in the present example) by means of a saw-like tooth arrangement as previously discussed, wherein a first set of teeth 72 projects from surface 68 of the housing 52 and a second set of teeth 74 projects from the surface 56 of carriage 54 each set of teeth 76 and 74 being equi-radially disposed (best seen in Figs. 4A-4C), said teeth being inclined in opposing fashions so as to provide sliding rotational displacement in one direction only.

Furthermore, the carriage 54 is formed with a pin 78 projecting from its top surface 66 and slideingly received within an arced groove 80 formed at the bottom surface 68 of the housing 52 whereby rotational displacement of the carriage 54 without the housing 52 is facilitated only between said three distinct positions wherein once rotated in said clockwise direction of arrow 72 will not permit rotation in a backward direction whereby the sample received within sample receiving well 62 and the reagent agent location 56 remain unexposed also after use. It is thus appreciated that the device illustrated in connection with the second example is also a one-time disposable article.

The example illustrated in this Figs. 8-10 discloses a different configuration of an assay device in accordance with the present invention, generally designated 90 principally formed with similar elements as disclosed in connection with the second example disclosed above in connection with Figs. 4-7, however differing in that it comprises two sample assay arrays. In the present example, the carriage is formed with a single sample-receiving well 94 (for sake of illustration illustrated by dashed lines) whilst the housing 96 is formed with a first sample-receiving well 98 and a first reagent agent location 100 extending on a common radii as the sample-receiving well 94 and further comprising a second sample-receiving well 102 and a second reagent agent location 104 also extending on the same radii as the sample-receiving well 94.

The arrangement is such that the carriage is slidelingly rotatable about the housing 96 in both directions as illustrated by arrowed line 108.

Other features of the assay device are substantially similar to those disclosed in connection with the previous example as illustrated in Figs. 4-7.

In this particular case, each sample assay array may comprise a different reagent agent within the reagent agent location 100 and 104.

Accordingly, when it is desired to expose the sample to a first reagent agent located within reagent agent location 100, the carriage is rotated in a counterclock direction of arrow 112 (Fig. 9A) whereby the sample-receiving well co-extends with the sample-introducing opening 98 to facilitate introducing of a sample into the sample- receiving well 94. Further rotation of the carriage in direction of arrow 114 (Fig. 9B) entails engagement of the sample contained in the sample-receiving well 94 with the reagent agent provided within the reagent agent location 100 whereby a reaction takes place to be viewed through the viewing window.

Likewise, if it is desired to expose the sample to a different reagent agent contained within reagent agent location 104, the carriage is rotated in a clockwise direction of arrow 116 (Fig. 10A) whereby the sample receiving well 94 coincides with the sample introducing opening 102 to facilitate introducing the sample into the sample- receiving well 102. Further rotation of the carriage in direction of arrow 118 (Fig. 10B) entails contact of the sample with the reagent agent contained within the reagent agent location 104 to provide a second indication viewable through the appropriate window of the second reagent agent location 104.

Like in previous examples disclosed hereinbefore, the sample-receiving wells and the reagent agent locations of both the sample assay arrays remain concealed at their respective positions to prevent contamination.

A fourth example is illustrated in Figs. 1 IA - 11C which is substantially similar to the second example of Figs. 4 - 7 and third example of Figs. 8-10 wherein a assay device 120 comprises two sample assay arrays 122 and 124 wherein the carriage is fitted with a first sample-receiving well 126 corresponding with the first sample assay array 122, and a second sample-receiving well 128 corresponding with the second sample assay array 124, said sample-receiving wells 126 and 128 extending along the same radii line however at different distances from the center a. For sake of clarity, said sample-receiving wells 126 and 128 are illustrated by dashed lines. Likewise, the first sample assay array 122 comprises a first sample introducing opening 132 and a first reagent agent location 134 co-radially extending with the first sample receiving well 126, and a second sample introducing opening 138 and a second reagent agent location 140 extending on the same radii as of the second sample receiving well 128 of the second sample assay array 124.

Each of the reagent agent locations 134 and 140 of the first and second sample assay array 122 and 124 respectively may hold a reagent agent dedicated for a particular analytical test or may hold the same reagent agent wherein different samples are introduced into the respective sample receiving wells 126 and 128.

The carriage is displaceable in a counterclockwise direction for initial, closed position (Fig. HA) into the second sample-introducing position (Fig. HB) and then further in a counterclockwise direction of arrow 146 into the assay position with both sample receiving wells 126 and 128 co-extend with the respective reagent agent locations 134 and 140 wherein two analyt tests are carried out simultaneously.

With further attention now directed to Figs. 12A -12C there is illustrated a fifth example of an assay device of the present invention generally designated 160 resembling the first example of Figs. 1-3, however comprising two parallely extending sample assay arrays 162 and 164. The first sample assay array comprises a first sample receiving well 168, illustrated by dashed lines, formed on the carriage 170. A first sample introducing opening 178 and a first reagent agent location 182 are formed respectively, on the housing 184 linearly aligned with said first sample receiving well 168. The second sample assay array 164 is composed of a second sample receiving well 188 formed on the carriage 170 and a sample introducing opening 190 and a reagent agent location 192 are formed on the housing 184, linearly aligned with said second sample receiving well 188 of the second sample assay array 164.

The assay device 160 is displaceable between three operative positions namely and initial, closed position (Fig. 12A) wherein both sample receiving wells 168 and 188 and both reagent agent locations 182 and 192 are sealingly concealed. Upon sliding displacement of the carriage 170 in direction of arrow 194 (Fig. 12B) both the sample receiving wells 168 and 188 coincide with the respective introducing openings 178 and 190 to allow introducing of a sample therein. Upon further displacement of the carriage in same direction of arrow 194 the sample receiving wells 168 and 188 coincide with both the reagent agent locations 182 and 192 of both sample assay arrays 162 and 164 respectively, wherein a reaction with the respective samples and the reagent agents contained within the reagent agent locations take place to be viewed through the appropriate openings.

The assay device 160 is fitted with the same features as of the first example namely being a one time disposable device wherein the carriage is slideable in one direction only and will not slide beyond its three respective positions.

Yet another example of an assay device according to the present example is illustrated in Figs. 13A and 13B disclosing a cylindrical structure. The device 200 comprises a cylindrical housing 202 coaxially receiving an inner carriage cylinder 204 which like in connection with the previous example is fitted with a one-way rotation arrangement for rotational displacement with respect to one another in a predetermined direction only as indicated by arrow 208. The housing 202 is fitted with a sample- introducing opening 210 and a reagent agent location 212 as discussed herein above. The reagent agent location is fitted with a see-through window.

The carriage 204 is fitted with a sample-receiving well 222 in the form of a cavity, the arrangement being such that said sample-introducing opening 210, reagent agent location 212 and sample-receiving well 222 constitute together a sample assembly 215. The housing 202 and the carriage 204 are coaxially disposed about axis A and wherein the sample-introducing opening 210, reagent agent location 212 and sample- receiving well 222 are equi-axially disposed about the axis A.

Rotating the housing 202 in direction of arrow 208 displaces the device between the three distinct positions as discussed above, namely a closed position wherein each of the sample receiving well 222 and the reagent agent location 212 is sealingly concealed, a sample introducing position wherein the sample receiving well 222 and the sample introducing opening coincide 210, and an assay position wherein the sample receiving well 222 coincides with the reagent agent location 212. The example of Fig. 13B is substantially similar to the example of Fig. 13 A with the exception that two sample assemblies 225A and 225B are provided, each comprising a sample-receiving well 230A and 230B in the form of a cavity formed in the inner cylinder 232, a said sample-introducing opening 238A and 238B and a reagent location 240A and 240B formed in the housing 246.

It is noted that components of each of the two sample assemblies 225A and 225B are equi-axially disposed about the axis A.

Other features of the devices of Figures 13A and 13B are substantially similar to those disclosed herein above in connection with the previous examples.

Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations, and modifications can be made without departing from the scope of the invention, Mutatis Mutandis.

Claims

CLAIMS:

1. An assay device for detection of at least one analyte in a sample, the device comprising a housing and a carriage displaceable with respect to one another and comprising at least one sample assay array, wherein one of said housing and said carriage comprises a sample receiving well and the other of said housing and said carriage comprises a sample introducing opening and a reagent agent location holding a reagent agent; the device comprising at least two operative positions: a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location.

2. An assay device according to claim 1, comprising three operative positions: an initial, closed position wherein each of the sample receiving well and the reagent agent location is sealingly concealed, a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location.

3. An assay device according to claim 1, wherein each sample assay array comprises at least one of a separate sample receiving well and a reagent agent location.

4. An assay device according to claim 3, wherein two or more sample assay arrays share at least one of sample receiving well and a reagent agent location.

5. An assay device according to claim 1 , wherein the housing and the carriage are rotatably slidable, wherein the sample receiving well, the sample introducing opening and the reagent agent location of a sample assay array are equi -radially disposed.

6. An assay device according to claim 5, comprising two or more equi-radially disposed sample assay array, wherein rotation of one of the housing and the carriage in one direction manipulates a first sample assay array and rotation in an opposite direction manipulates a second sample assay array.

7. An assay device according to claim 5, comprising two or more sample assay arrays each of which disposed about a diverse radii.

8. An assay device according to claim 1 , wherein the housing and the carriage are coaxial cylinders rotatably slidable, wherein the sample receiving well, the sample introducing opening and the reagent agent location of a sample assay array are equi- axially disposed in the housing and carriage.

9. An assay device according to claim 1 , wherein the housing and the carriage are linearly slidable, wherein the sample receiving well, the sample introducing opening and the reagent agent location of a sample assay array are linearly disposed.

10. An assay device according to claim 9, comprising at least two sample assay arrays parallely disposed along the housing and carriage.

11. An assay device according to claim 10, wherein one of the housing and the carriage is formed with longitudinal slots for sliding engagement with the other of housing and carriage.

12. An assay device according to claim 10, wherein a locking arrangement is provided such that the carriage is displaced with respect to the housing between three distinct positions.

13. An assay device according to claim 12, wherein the locking arrangement is a one-way displacing ratchet mechanism.

14. An assay device according to claim 1, wherein a see-through window is provided over the reagent agent location.

15. An assay device according to claim 14, wherein the see-through window is covered by a removable light shield so as to prevent exposure of the reagent agent to light prior to use.

16. An assay device according to claim 1, wherein the carriage does not project from the housing at any of the three positions.

17. An assay device according to claim 1, wherein the reagent agent location remains unexposed at any of the three positions.

18. An assay device according to claim 1, wherein the sample receiving well is unexposed at the initial, closed position.

19. An assay device according to claim 1 , wherein a visual indicator is provided to indicate a respective position of the device.

20. An assay device according to claim 1 , wherein a motion restricting arrangement is provided for restricting displacement of the carriage and housing between only said three operative positions.

21. An assay device according to claim 18, wherein the motion restricting arrangement comprises a projection from a surface of one of the housing and carriage slidingly received within a groove formed in a flush mating surface of the other of said housing and carriage.

22. An assay device according to claim 1, wherein the reagent agent is suited for detecting conditions of oral malodor.

23. An assay method for detection of an analyte or determining its concentration in a sample, the method comnmprising:

(b) introducing the sample through the sample introducing opening into the sample receiving well;

(c) manipulating the device into the assay position for reaction to take place between the sample and the reagent agent;

(d) observing the result of the interaction between sample and reagent agent.

24. A method according to claim 23, wherein the device comprises three operative positions: an initial, closed position wherein each of the sample receiving well and the reagent agent location is sealingly concealed, a sample introducing position wherein the sample receiving well and the sample introducing opening coincide, and an assay position wherein the sample receiving well coincides with the reagent agent location and wherein a further step before step (b), namely manipulating the device into the sample introducing position.

25. A method according to claim 23, wherein the device comprises at least two sample assay arrays and wherein steps b) to d) are carried out for each of the sample assay arrays.