WO2009050435A1

WO2009050435A1 - Testing apparatus and method with dosing mechanis

Info

Publication number: WO2009050435A1
Application number: PCT/GB2008/003420
Authority: WO
Inventors: John Amey; Kevin Quinlan; Emma Whitworth
Original assignee: Porvair Filtration Group Limited; British Biocell International Limited
Priority date: 2007-10-16
Filing date: 2008-10-09
Publication date: 2009-04-23
Also published as: GB2453744B; GB2453744A; GB0720212D0

Abstract

In order to analyse a sample to detect a target, a test apparatus has a test member having an indicator responsive to the target, a dosing member operable to receive the sample, and a dosing mechanism operable to cause the dosing member to be moved into contact with test member and then moved out of contact with the test member, whereby up to a predetermined amount of at least a part of the sample is applied to the test member.

Description

TESTING APPARATUS AND METHOD WITH DOSING MECHANISM

BACKGROUND

[0001] The invention relates to apparatus and methods of testing for the presence of a target in a sample.

[0002] For example, apparatus and methods are known for resting a sample in the form, for example, of a fluid. The fluid can, for example, be a bodily fluid (e.g., blood) that may contain a toxin or an indicator of a disease or other medical condition. Devices for carrying out such tests are known and can provide reliable test results. One type of such a device is known as a lateral flow assay device. However, in order to achieve accurate test results, specialist knowledge may be required to carry out the test. This may, for example, be as a result of one or more of a need to follow a predetermined ordering or timing of the operation of a test device, and/or to have a predetermined quantity of the sample for a test and/or to avoid the contamination of the result and/or to avoid spillage of a potentially toxic or infectious sample.

[0003] Accordingly, there is a need for an improved apparatus and method of testing a sample to detect a target therein.

[0004] The present invention seeks to provide an improved test apparatus and method that can provide yet more reliable test results, even where expert supervision is not available. SUMMARY

[0005] An aspect of the invention provides an apparatus for testing a sample to detect a target. The apparatus includes: a test member having an indicator responsive to the target; a dosing member operable to receive the sample; and a dosing mechanism operable to cause the dosing member to be moved into contact with test member and then moved out of contact with the test member, whereby up to a predetermined amount of at least a part of the sample is applied to the test member.

[0006] Another aspect of the invention provides a method of testing a sample to detect the presence of a target. The method includes: applying a sample to be tested to a dosing member; moving the dosing member into contact with a test member, which test member has a visually detectable indicator responsive to the target; and moving the dosing member out of contact with the test member, whereby up to a predetermined amount of at least a part of the sample is applied to the test member.

[0007] In an embodiment of the invention, the dosing mechanism can be operable to provide one controlled dose only of at least a selected part of the sample is applied to the test member, thereby facilitating accurate tests to be performed.

[0008] An embodiment of the invention can provide a secure and safe apparatus and method for carrying out tests in a reliable manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings. Figure 1 is an isometric exploded diagram of an example of a test device;

Figure 2 is an enlarged view of parts of the test device of Figure 1;

Figure 3 is a schematic representation of part of the component of the test device;

Figures 4A, 4B and 4C represent first, second and third stages, respectively, in a method of using the test device; Figures 5 A, 5B and 5C represent a cross section of part of the device at the first, second and third stages, respectively;

Figure 6 is an isometric external view of the test device at the first stage; and

Figure 7 is an isometric external view of the test device at the third stage.

DETAILED DESCRIPTION

[0010] An example embodiment of a testing apparatus and method for analysing a sample to detect a target will be described in the following with reference to the accompanying drawings, which show one example embodiment of a testing device. It will be appreciated from the following description that many variations and modifications to the specifically described example embodiment are possible.

[0011] Figure 1 is an exploded isometric view of the example embodiment of a testing device 10. The present example testing device could be described as a lateral testing device as will be explained later. The example embodiment of the test device 10 shown in

Figure 1 comprises a cover member 12. The cover 12 is slidably mounted on an upper housing portion 14 of a device housing 15. The device housing 15 comprises the upper housing portion 14 and a lower housing portion 16. Within the housing 15, when assembled, a dosing mechanism 20 is provided, which dosing mechanism 20 includes a support structure 18 and a dosing member 19. Also contained within the housing is a porous member in the form of a test member 22.

[0012] The cover 12 can, for example, be made of a plastics material, for example a hydrophobic plastics material. Examples of suitable plastics materials include,

Acrylonitrile-butadiene-styrene (ABS), Polyaryletherketone (PEEK), Polybutylene terephthalate (PBT), Polyethersulphone (PES) and Polyethylene terephthalate (PET).

The cover 12 can be transparent, or can be partially translucent or opaque. Suitable plastics materials for a transparent cover include polycarbonates, acrylics and copolyesters. The example of the cover shown is provided with a number of formations as will now be described.

[0013] A manually operable portion 24 is provided for a user to slide the cover. In the example shown in Figure 1, the manually operable portion 24 is a hole that can be gripped, for example, by a user between a finger and thumb. [0014] Various apertures and windows are provided in the example of the cover shown in Figure 1. A first, sample, aperture 26 provides for the insertion of a sample into the test device 10 in a manner to be described later. A second, buffer, aperture 28 provides for the insertion of a buffer medium in the device 10, as also to be described later. A transparent window 30 is provided at one end of the slidable cover. Between the apertures 26 and 28 and the window 30, a solid portion 29 of the cover 12 is provided.

[0015] In the example shown in Figure 1, the cover 12 is provided with two lateral flanges 46 that engage within grooves 44 provided under stepped returns 42 on the top of the upper housing portion 14. The grooves 44 define a channel within which the slidable cover may slide. In the example shown in Figure 1, the upper portion of the housing 40 is provided with first and second flexible non-return latches 33 which engage with ratchet formations (not shown) on the underside of the cover 12, whereby the cover may be slid in a single direction only, that is from the lower right to the upper left in Figure 1.

[0016] In the example shown, the upper housing portion 14 is provided with a first aperture 34 in a middle region thereof. A first part 35 of the first aperture 34 is arranged to cooperate with the first aperture 26 of the cover 12 and to receive a carrier 52 of the support structure 18 for the insertion of the sample as will be described later. A second part 36 of the first aperture 34 forms an viewing opening and cooperates with the window 30 of the cover 12 to enable viewing of test results as will be described later. Sloping side portions of the upper housing portion that drop down into the second part of the aperture 36 are provided with indicator marks 37 and 38 that identify positions of indicator lines on the test member 22 to be described later. A second aperture 40 in the upper surface 32 of the upper housing portion 14 is arranged to cooperate with the second aperture 28 of the cover 12 for the insertion of the buffer medium as will be described later. Openings 90 can be provided in the side walls 31 of the upper housing portion 14 for engagement with latching formations 92 provided on the lower housing portion 16 during assembly of the device 10 as will be described later. [0017] The example of the lower housing portion 16 shown in Figure 1 is provided with a number of formations. A wall portion 80 and wall portions 82, in combination with ridges 85, define a channel for receiving the test member 22. The wall portion 80 further forms a receptacle 81 for receiving the buffer medium as will be described later. Side walls 91 of the lower housing portion 16 are provided with formations for locating the support structure 18 of the dosing mechanism 20. These formations include slots 86 for receiving legs 48 of the support structure 18 and recesses 88 for receiving stabilising flanges 50 of the support structure 18.

[0018] The upper and lower housing portions 14 and 16 can, for example, be made of a plastics material, for example a hydrophobic plastics material. Suitable plastics materials include those identified earlier.

[0019] Figure 2 illustrates an example dosing mechanism 20 and an example test member 22 in more detail.

[0020] As mentioned above, the dosing mechanism comprises a support structure 18 and a dosing member 19.

[0021] In the example shown in Figure 2, the support structure 18 of the dosing mechanism 20 comprises a frame 60 that includes side members 61 and cross members 62. The aforementioned legs 48 and stabilising flanges 50 of the support structure that interact with the slots 86 and recesses 88 of the lower housing portion 16 to locate the support structure 18 are, in the example shown, provided on the side members 61 of the frame 60. Also provided on the frame 60 are springs 63 which, in the example shown, interconnect the side members 61 to a carrier member, carrier, 52.

[0022] Also, in the example shown, the carrier member 52 is substantially rectangular and is formed with walls 51 that, in the middle thereof, define an opening 54 for receiving the dosing member 19. The walls 51 of the carrier member 52 can be formed with a Hp at the bottom thereof on which the dosing member 19 rests. The walls 51 and the dosing member can be dimensioned such that the dosing member is a friction fit within the walls 51. Alternatively, or in addition, the walls can be formed with a groove (not shown) around the lower end thereof into which the dosing member can be pressed.

[0023] The upper edges of walls 51 on the sides of the carrier member 52 can be provided with cam formations 56 that include a sloping edge at one side thereof, and a vertical edge 58 at the other side thereof, whereby an interaction (to be described later) between the cam formations 56 and corresponding formations (to be described later) on the cover 12 enable the carrier 52 to be urged in a downwards direction (in the orientation shown in Figure 2) against the resilience of the springs 63 (as will be described later).

[0024] It should be noted in the description of Figure 2 that the use of the term "member" has been used to describe various features of the support structure 18. It is to be understood that the use of the term "member" in this document does not imply that the

"member" is a discrete component, but that it can form part of an integral structure. For example, in the present example, the support structure 18 can be formed as an integral moulding of a hydrophobic plastics material. Suitable plastics materials include those identified earlier. However, in other examples the support structure could be assembled from one or more separate component members.

[0025] In the present example, the dosing member 19 is formed as a laminated frit that includes a first layer 94, that acts as a sample receiving and/or reservoir and/or filter layer and a second layer 96, that acts as a sample dosing layer. The frit can be made, for example of sintered thermoplastic plastics material.

[0026] In an example process for creating the first layer 94 of such a dosing member

19, a sintered porous polymer material can be prepared by sintering thermoplastic granules, powder or pellets to form a substrate. The ability of a thermoplastic polymer to be sintered can be determined from its melt viscosity, whereby the higher the melt viscosity the easier it becomes to form a sintered porous structure. Suitable thermoplastics that can be used to provide the porous polymer substrate include, but are not limited to, polyolefins, nylons, polycarbonates, polyether sulfones, polystyrene and mixtures thereof. A preferred thermoplastic is a polyolefin. Examples of suitable polyolefins include, but are not limited to: ethylene vinyl acetate; ethylene methyl acrylate; polyethylenes; polypropylenes; ethylene-propylene rubbers; ethylene- propylenediene rubbers and mixtures and derivatives thereof. A preferred polyolefin is polyethylene. Examples of suitable polyethylenes include, but are not limited to, low density polyethylene, linear low density polyethylene, high density polyethylene, ultrahigh molecular weight polyethylene, and derivatives thereof. The first layer 94 could be made, for example, from a porous polymer material known as Vyon® and available from Porvair Filtration Group Limited.

[0027] In an example embodiment, the second layer 96 of such a dosing member 19 can be formed from a spongy pad of a porous material. Suitable example materials include microporous polymeric films, which can be fibrous or sponge-like, or with a structure formed by a phase inversion or track etch process. In another example, a porous pad of another material, for example a wood or paper based material could be used.

[0028] As indicated above, the dosing member 19 can be formed as a laminated frit that includes a first layer 94 and a second layer 96. In a manufacturing process, the two layers can be formed separately and then be laminated together. Each layer can thereby be designed to have specific characteristics. In the example embodiment, the sample receiving layer 94 is relatively rigid compared to the dosing layer 96 and forms a reservoir for the sample to be tested. The first layer can also be operable to act as a filter to remove at least some potential contaminants from the sample. In the example embodiment, the dosing layer 96 is relatively spongy with respect to the first layer 94 and serves to hold a volume of the sample to the applied to the test member 22, wherein can then be squeezed out of the dosing layer 96 when the dosing layers is pressed onto the test member 22. The second layer can also act as a filter to filter out potential contaminants from the sample.

[0029] Figure 3 is a schematic representation of a cross section of part of an example dosing member 19 showing the first layer 94 and the second layer 96.

[0030] In the example shown, the composition of the first layer 94 is chosen to have a particles 194 of an appropriate size, and/or with inter-particle spaces 195 of an appropriate size, to act to filter out selective contaminants in the sample that are to be removed before testing. The inter-particle spaces act to form a reservoir for the sample. The first layer has a relatively stable and rigid structure that is more resistant to compressive forces than the second layer 96.

[0031] In the example shown, the second layer 96 is a porous compressible layer ,for example a fibrous layer) formed, for example from a material such as a filter paper, cellulose, nitrocellulose, glass fibre, a polymer, etc. The second layer 96 could have a structure other than a fibrous structure, for example an open sponge-like structure. The second layer can also be configured to hold back or further filter out particles in the sample to be tested. For example, where the sample to be tested is blood, the second layer 96 could be configured to separate out blood cells from blood plasma. The second layer

96 provides a structure with spaces for receiving at least a part of the sample (for example minus contaminants filtered out by first layer 94) but is compressible so that the part of the sample contained therein can be squeezed out. The second layer 96 is dimensioned to have a predetermined capacity whereby up to a predetermined amount, or volume, or dose, of the sample (or the part of the sample contained therein) can be deposited on the test member 22 as will be described later.

[0032] The second layer 96 can have a different thickness compared to the first layer

96. In the example shown the second layer 96 is thinner than the first layer 94. As indicated above, the first layer 94 can act as a reservoir for the sample to be tested and the second layer 96 can be configured (e.g., dimensioned) such it can hold and release a predetermined amount, volume or dose, of at least part of the sample to the test member 22.

[0033] In operation, the boundary between the first layer 94 and the second layer 96 (hereinafter referred to as the inter-layer boundary 95), and potentially also the region of the second layer 96 adjacent the inter-layer boundary 95, acts to restrict the volume of the sample that it available to be transferred to the test member 22 from the second layer 96 as will be described later.

[0034] The actually structure of the first layer 94 and the second layer 96 can be chosen according to desired application. For example, where the sample is blood, and the test to be performed is to test for a target in the blood (for example a specific antibody or antigen) the particle sizes for the particles in the first layer 94 and the solid to air ratio of the second layer 96 can be chosen such that the blood cells are filtered out, and the blood plama (including the antibody or antigen) is transferred in the part of the sample transferred to the test member 22 from the second layer 96.

[0035] An example range of particle sizes for polyethylene for the first layer 94 could be in the range of lOμm to 800μm, for example in the range of 30μm to 500μm, or for example in the range of lOOμm to 300μm. A fine pore structure might be made for a range of lμm to lOOμm, a medium pore structure from lOOμm to 300μm, and a coarse structure from 300μm to 800μm. In one example, a coarse structure, i.e. 300μm to 800μm can be used.

[0036] In an example process for making the first layer of a dosing member 19, polymer particles can be made, for example, by cryogenically or ambiently grinding a suitable polymer material and then screening the result to ensure a proper particle size distribution for the substrate. [0037] The resulting particles can then be placed in a mould, or multiple moulds. The moulds can be made, for example, of carbon steel, stainless steel, brass, or aluminium, and may have a one or more cavities. The mould filling can be assisted by using commercial powder handling and vibratory equipment. Thermal processing can then be carried out by introducing heat to the mould, using any appropriate controllable heating means. Electrical resistance heating, electrical induction heating, or steam heat may be used. The applied heat is controlled as appropriate to allow softening of the polymer particles and allow inter-particle binding to occur. Processing of parts with consistent porosity, strength, and flow characteristics is dependent on carefully considered application of commercial process control equipment. Control of the temperature cycle must allow consistent part manufacture such that there are no problems with under-processing which leads to weak, unsintered parts, or overprocessing, leading to glazed, non-porous parts. At the end of this process, the resulting frits can be removed from the mould(s).

[0038] As an alternative to a process using moulds, the polymer particles can be laid down on a suitable belt and passed through a sintering oven to make continuous sheet which can be later fabricated into required shapes. In this case, heating as described with respect the mould process can be applied and the same considerations with regard to the control of the temperature cycle.

[0039] The lamination of the first layer 94 and the second layer 96 to form the dosing member 19 can be effected as part of the manufacturing process by applying the second layer 96 to the first layer 94 before this cools, whereby the first layer 94 is still sticky as a result of the softening of the particles of the first layer 94 and the second layer 96 then bonds to the first layer 94.

[0040] The action of the dosing member 19 can be enhanced by rendering it hydrophilic. This can be achieved by coating the internal surfaces of the dosing member

19 with polar functional groups such as hydroxylic acids, amines, amides, ketones etc. The internal surfaces of the first and second layers 94, 96 of the dosing member 19 can be coated, for example, by using a variety of standard laboratory oxidation reagents or by subjecting the dosing member 19 to polar free radicals in a gas plasma.

[0041] Returning to Figure 2, the dosing member 19 is shown as being slightly bowed. This can be achieved though the application of pressure and heat to the assembled laminar dosing member. Although in the present example the dosing member has a substantially rectangular shape and is slightly bowed, in other examples it could have any other suitable shape. Merely by way of example it could be round, triangular, hexagonal, etc. It could also be substantially planar, or have more than one radius of curvature.

[0042] Figure 2 also shows an example of the test member 22 (which in the present example forms an elongate test strip comprising porous material, which forms a lateral flow matrix). In the example shown, a porous test layer 65 (for example of a material such as a filter paper, cellulose, nitrocellulose, glass fibre, a polymer, etc.) is strengthened at a first end by a upstream zone 64 formed by a layer of porous material (for example of the same or a similar material) that serves to hold the buffer medium when this is added. At the opposite end by a downstream zone 70, formed by a layer of, for example, the same or a similar porous material can be provided. A receiving zone 68 of the test layer 65 can be arranged to receive up to a predetermined amount of at least a part of the sample from the dosing member 19. Between the receiving zone 68 and the upstream zone 64, a transfer zone 66, formed in the present example by a further layer of the same or a similar porous material, can be provided. The porous material of the transfer zone 66 can be provided with a dried labelled reagent. Between the receiving zone 68 and the downstream zone 70, a detection zone 74 can be provided. In the present example the detection zone 74 is configured as one or more test lines. The detection zone 74 can be provided with one or more binding agents configured to bind with and immobilise the target in the sample to be tested. Downstream of the detection zone 74, a control zone 76 can be provided. The control zone 76 can be provided with a control agent as will be described later. [0043] In operation, up to a predetermined amount or volume of at least part of the sample is deposited around the receiving zone 68 on the test layer 65. The sample deposited on the receiving zone 6$ tends to wick downstream towards the downstream zone 70 and in doing so passes through the detection zone 74. As it passes through the detection zone, the binding agent(s) bind with and immobilise any of the target in the porous material of the detection zone 74 as bound pairs. Then a buffer material is added to the porous material of the upstream zone 64 adjacent the first end of the test member 22. The buffer material is received by and wicks along the porous material of the upstream zone 64 and the transfer zone 66 and through the sample receiving zone 68 to the detection zone 74. In doing so, the buffer medium is operable to mobilise the labelled reagent in the transfer zone 66 and to carry this to the detection zone. If the target was present in the sample, and bound pairs have been formed in the detection zone 74 as described above, the labelled reagent reacts with any bound pair(s) to cause the label of the labelled reagent to manifest itself by way of a change of colour or other indication in the detection zone 74. The label of the labelled reagent can, for example, be a known visibly detectable label such as an enzyme, a chromophore, a fluorophore, etc. The unlabeled control agent of the control zone is configured to react with the labelled reagent carried by the buffer to provide a visible indication that the buffer material has passed the detection zone 74 into the control zone 76, whereby a user is able to detect that the test is complete, irrespective of whether a positive or negative test result is indicated by the detection zone 74

[0044] The test lines formed by the detection zone 74 and the control zone 76 are aligned with the visible markers 37, 38 in the upper housing portion whereby a user can identify through the transparent window 30 whether or not the test is complete and whether, or not the test positive.

[0045] When the device shown in Figure 1 is assembled, the test member 22 is firstly inserted into the lower housing portion 16 to be located by the walls 80 and 82 and the protuberances 85. The support structure 18, which is provided with the dosing member 19 to form the dosing mechanism 20, is then inserted over the test member 22 and is located by means of the slots and recesses 86 and 88 engaging with the legs and flanges 48 and 50 as described earlier. The cross members 62 serve as pinch elements to hold the test member 22 in place during and after assembly of the test device 10.

[0046] The upper housing portion 14 can then be located over the assembly and clicked into place through the engagement of the wedge shaped formations 92 on the side walls 91 of the lower housing portion 16 within the openings 90 in the side walls 31 of the upper housing portion 14. The cover 12 can then be applied to the upper housing portion 14 by inserting the gripable end 24 of the slidable cover 12 at the lower right hand end of the slots 44 and then being slid to the left as shown in Figure 1 whereby the non-return ratchets 33 engage with the corresponding ratchet formations (not shown) on the underside of the cover 12 to ensure that the cover 12 is movable in a first direction only. Sliding of the slidable cover 12 is stopped when the right hand end of the slidable cover 12 (as shown in Figure 1) aligns with the right hand end (as shown in Figure 1) of the upper housing portion 14.

[0047] Figures 4 and 5 represents three stages of operation of the example test device 10. Figure 4 comprises Figure 4A, Figure 4B and Figure 4C, each representing a respective one of those stages showing the test device 10 partially in cross section. Figure 5 comprises Figure 5A, Figure 5B and Figure 5C, each representing a respective one of those stages showing details of the test device 10 partially in cross section.

[0048] Figure 4A shows the assembled test device 10 in the initial position (as described above) where the right hand end of the cover 12 aligns with the right hand end of the upper housing portion 14. In this position, the non-return ratchets 33 on the upper housing portion 14 are engaged with corresponding formations (not shown) on the underside of the cover 12. In addition, the cam formations 56 of the carrier 52 are engaged within corresponding recessed cam formations 97 on the underside of the cover 12. [0049] Figure 5A illustrates, in more detail, an example of the inter-engagement of the cam formations 56 on the carrier 52 with the cam formation 97 of the cover 12. Here it can be seen that the left hand edge of the cam formation 97 is formed with a vertical edge that acts together with vertical face 58 of the cam formation 56 to further resist slidable movement of the slidable cover 12 towards the right as shown in Figure 4 A and Figure

5A. Accordingly, in this position, both the cooperation of the non-return latches 33 with the corresponding cam formations (not shown) on the underside of the cover 12, and the cooperation of the cam formations 56 and 97 of the carrier 52 and cover 12, respectively, both act to prevent movement of the cover 12 to the right.

[0050] In the position shown in Figures 4A and 5 A the first aperture 26 of the cover is aligned with the first part 35 of the first aperture 34 of the upper housing portion and the carrier 52, whereby a sample to be tested may be inserted through the first aperture 26 in the cover 12, the first part 35 of the first aperture 34 of the upper housing portion and onto the upper surface of the dosing member 19. Due to the hydrophobic nature of the plastics material using for the cover 12 and the upper housing portion 14, and the hydrophilic nature of the dosing member 19, a water-based sample will not adhere to the plastics material of the cover 12 and the upper housing portion 14, but will be quickly drawn into the hydrophilic first layer of the dosing member 19.

[0051] As further shown in Figure 5A, in this position, the dosing member 20 carried by the carrier 52 is spaced from the sample receiving zone 68 of the test member 22. This is as a result of the carrier 52 being forced through the first part 35 of the first aperture 34 of the upper housing portion 14, the shape of which is configured to conform to the lower surface of the cover 12 so that the walls 51 of the carrier 52 in combination with the cover 12 form a channel, or funnel, to direct all of the sample to the upper surface of the dosing member 19. In this position, as the lower surface of the dosing member 19 is spaced from the test member 22, no transfer of sample between the dosing member 19 and the test member 22 occurs. [0052] In the position shown in Figure 4A and 5 A, the second aperture 28 of the cover 12 overlies the upper surface 32 of the upper housing portion 14, whereby no access is provided to the interior of the housing 15 via the buffer aperture 22.

[0053] After insertion of the sample, the user is able to take hold of the manual formation 24 of the slidable member 12 and to slide the slidable member to the left as shown in Figure 4. The non-return ratchet and cam formations 33, 56 and 97 are configured to permit movement of the cover to the left with respect to the housing as shown by comparison of Figures 4A and 4B.

[0054] Figure 4B illustrates an intermediate position partway through sliding the slidable cover to the left. In the position shown in Figure 4B, the cam formation 56 on the upper portion of the carrier 52 is forced down by the corresponding cam formation 98 on the underside of the slidable cover 12 having the effect of forcing the carrier member vertically downwards against the resilient force of the springs 63 which tend to urge the carrier upwards, that is towards the cover 12, and away from the test member 22. Comparing Figures 4A and 4B will show the change in the relationship of the springs 63 verses the carrier member 52, showing the effect of the carrier member 54 being forced downwards against the force of the springs 63.

[0055] Accordingly, in the position shown in Figure 4B, the dosing member 19 is in contact with the test member 22. This is shown in more detail in Figure 5B, where it can be seen that the carrier member 52 is pressed downwards by the cam formation 56 thereof being pressed upon by the lower surface 98 of the cover 12. The downward movement of the carrier member presses the dosing member against the receiving zone 68 of the test layer 65 of the test member 22. The test member 22 at this position is backed by an abutment 84 whereby the dosing member 19 tends to squash the second layer 96 of the dosing member 19, whereby good contact with the test zone of the test member 22 is facilitated and good transfer of a predetermined amount, or volume, of the sample to the test member 22 is facilitated by squeezing the sample out of the second layer onto the test member 22.

[0056] After the sample is deposited on the receiving zone 68, the sample tends to wick downstream towards the downstream zone 70 and in doing so passes through the detection zone 74. As it passes through the detection zone, the binding agent for a given target is operable to bind with and immobilise any of the target in the porous material of the detection zone 74 as a bound pair.

[0057J Figure 4C shows the effect of the continuation of the sliding movement of the cover 12 to an end position where the cam portions 56 of the carrier 52 are received within cam formations in the form of recesses 99 of the cover 12. In this position (see also Figure 5C), the carrier member 52 is urged once more by the spring members 63 to a position where the lower surface of the dosing member 19 is spaced from the test member 22 so that no further transfer of sample between the dosing member 19 and the test member 22 occurs. In this position, the carrier 52 and the dosing member 19 are located below the solid portion 29 of the cover 12, whereby access thereto is prevented.

[0058] The construction of the dosing member 19 having the first layer 94 and the second layer 96 as described above can control the dose, or amount, of sample available to be transferred to the test member 22. Also, the operation of the cam formations whereby the dosing member is tapped, or dabbed, onto the test member during movement of the cover 12 means that one dose of the sample is applied to the test step. Accordingly, accurate control of the dose of the sample applied to the test member 22 is provided, whereby up to a predetermined volume of the sample is deposited around the receiving zone 68 on the test layer 65 of the test member 22.

10059] As further illustrated in Figure 4C and Figure 5C, the detection and control zones 74 and 76 are visible to the user through the transparent window 30 and the part 35 of the opening in the upper housing portion 14. As a result, the user is able to verify if and when a positive or negative test result is obtained.

[0060] In the position shown in Figure 4C, the aperture 28 in the upper housing portion is aligned with the buffer receptacle 81 whereby a buffer medium can be inserted through the aperture 28 and received onto the test member 22 in the region of the upstream zone 64 of the test member 22. The wall portion 80 of the lower housing portion 16 forms a receptacle 81 that serves to contain the buffer medium as it is being absorbed by the porous material of the upstream zone 64. The buffer material absorbed by the porous material of the upstream zone 64 is then drawn into and through the transfer zone 66 where it releases, or mobilises, the labelled reagent, which it then carries to the detection zone 74.

[0061] As described earlier, if, for example, a given target is present in the sample and had been bound to the binding agent in the detection zone, the labelled reagent will react with the bound pair and an indications, for example a change of colour of one or more test line(s), formed in the detection zone 74 can be caused to occur.

[0062] In this example, the control zone 76 downstream of the detection zone 74 can be responsive to the labelled reagent in the buffer medium to change colour to indicate that the labelled reagent (and therefore the buffer medium) has reached that test line, whereby the change of colour, or lack of change of colour, of the detection zone 74 responsive to the intended target(s) can be given as a clear indication of the presence, or otherwise, of the target in the sample. As indicated above, the detection zone 74 and the control zone 76 are aligned with the visible markers 37, 38 in the upper housing portion, whereby a user can identify through the transparent window 30 whether or not a positive test has been performed.

[0063] Figure 6 is a schematic isometric view of the test device in the first position shown in Figure 4A, as viewed from the exterior, with the first aperture 26 in the cover 12 aligned with the dosing member 19 through the first part 35 of the first aperture 34 in the upper housing portion 14. In this position, the sample 100 (e.g., blood) can be introduced to the dosing member via the first aperture 26 in the cover 12 and the first part 35 of the first aperture 34 in the upper housing portion 14. Also, in this position, the second aperture 28 is blanked off by a solid portion of the upper surface 32 of the upper housing portion 14. In the position shown in Figure 6, the transparent window 30 is aligned with a blank portion of the upper surface 32 of the upper housing portion 14.

[0064] Figure 7 is a schematic isometric external view of the test device in the position shown in Figure 4C. In this position, the fist aperture 26 in the cover 12 is aligned with a solid blank portion of the upper surface 32 of the upper housing portion 14, preventing further access to the inside of the housing via the first aperture 26 in the cover

12. The second aperture 28 in the cover 12 is aligned with the aperture 40 in the upper housing portion 14 and with the receptacle 81 in which the first support portion 64 of the test member 22 is located. In this position, the buffer material 102, for example water, may be inserted via the second aperture 28 in the cover 12 and the aperture 40 in the upper housing portion 14 to the first support portion 64 of the test member 22. In the position shown in Figure 7, the transparent window 30 is then aligned with the second part 36 of the first aperture 34 in the upper housing portion 14 and the detection and control zones 74, 76 on the test member 22.

[0065] Accordingly, there has been described an example of a test device that includes a number of technical advances. Such a test device can enable testing for a target substance in a sample to be tested in a full-proof manner, whereby the device itself defines the order in which various operations are to be performed, and enables secure and accurate tests to be performed. A test can be performed in a controlled and predictable manner such that the sample can be taken up rapidly by the hydrophilic dosing member. Up to a predetermined quantity of at least a part of the sample can be applied to the test member in a rapid and predictable manner through the use of the dosing member and the dosing mechanism. The supply of a controlled amount of the sample to the means that the test results are predictable and accurate.

[0066] In one example application a sample can be a whole blood sample and a target that is being tested for could be one or more blood components e.g., an analyte or antibody. The buffer medium can, for example be a buffered saline solution.

[0067] However, it will be appreciated that the present invention is not limited to use in testing blood samples, or for testing sorts of targets identified above. Embodiments of the invention can be provided for a wide range of targets such as specific molecules, toxins, contaminants, indicators, etc., that can be carried by a liquid, for example a water based liquid, wherein the liquid forms the sample and the specific molecules, toxins, contaminants, indicators, etc., form the target. The test device can be adapted to the particular test to be performed by providing an appropriate dosing member and an appropriate test member having appropriate test indicators for indicating the presence of the target.

[0068] Many variations may be made to the examples, described above while still falling within the scope of the invention.

For instance, in the described example the buffer medium is introduced through a second aperture in the housing. However, in another example the buffer medium could be held within a reservoir within the test device that is opened when the cover is moved to a second position corresponding generally to that shown in Figure 7. For example the buffer medium could be held within a flexible blister (not shown) located in the area of the receptacle 81 and this could be pierced by inserting a probe through the second aperture 28 in the cover 12 and aperture 40 in the upper housing portion 14. As a further alternative, the aperture 28 in the cover 12 could be replaced by a resiliently mounted probe that flexes downwards through the aperture 40 in the upper housing portion 14 to pierce such a blister, releasing buffer medium held therein. [0069] In the described example, the test member 22 is an elongate linear test member, and the housing is designed accordingly, whereby the slideable cover 12 is slideable linearly. However, in another embodiment the test strip could be arcuate and the test device could be designed as a disc-shaped device, whereby the cover could be configured as a dial or disk that rotates with respect to a circular housing. In this case, the first and second openings for the sample and the buffer could be arranged at different circumferential positions on the cover and the housing, whereby access for insertion of a sample is provided at a first relative rotational position of the cover and the housing, and access to for insertion of a buffer is provided at a second relative rotational position. The contacting of the dosing member and the test member could be caused to occur at an intermediate relative rotational position between the first and second positions. The cover and the housing could be provided with respective cooperating formations (for example inter-engaging ratchet formations) to ensure that relative rotation of the cover and the housing only occurs in a direction that passes from the first to the second position via the intermediate position.

[0070J In the described example, the cover 12 is provided externally to the housing. However, in another embodiment, the cover could be at least partially covered by the external surface of the housing, whereby the cover is operable only to cover the openings for the sample and/or the buffer.

[0071] It will be apparent that many modifications and alternatives are possible within the scope of the claimed invention.

Claims

1. A test apparatus for testing a sample to detect a target, the apparatus comprising: a test member having an indicator responsive to the target; a dosing member operable to receive the sample; and a dosing mechanism operable to cause the dosing member to be moved into contact with test member and then moved out of contact with the test member, whereby up to a predetermined amount of at least a part of the sample is applied to the test member.

2. The test apparatus of claim 1, comprising a housing and a moveable member that is moveable with respect to the housing and is operable to act on the dosing mechanism to cause the dosing member to be moved into contact with test member and then moved out of contact with the test member.

3. The test apparatus of claim 2, wherein the moveable member comprises a cover, the cover including an opening providing access to the dosing member for receipt of the sample in a first position, and preventing access to the dosing member in a second position.

4. The test apparatus of claim 3, wherein the moveable member and the dosing mechanism are provided with cam formations that are mutually interoperable to cause the dosing member to be moved into contact with test member and then moved out of contact with the test member in response to movement of the moveable member.

5. The test apparatus of claim 4, wherein the cam formations are configured to permit movement of the moveable member in a first direction with respect to the housing and to resist movement of the moveable member in a direction opposite to the first direction with respect to the housing.

6. The test apparatus of any of claims 3 to 5, wherein the moveable member is configured to act on the dosing mechanism to cause the dosing member to be moved into contact with test member and then moved out of contact with the test member during movement of the moveable member between the first and second positions.

7. The test apparatus of any of any of claims 3 to 6, configured to enable a buffer medium to be applied to the test member in the second position.

8. The test apparatus of any of claims 2 to 7, wherein the moveable member is a slidable cover.

9. The test apparatus of any preceding claim, wherein the dosing mechanism comprises a carrier portion for carrying the dosing member and spring elements, the spring elements being configured to urge the carrier portion away from the test member to cause engagement of the mutually interoperable cam formations.

10. The test apparatus of any preceding claim, wherein the dosing member comprises a first layer operable to receive the sample and a second layer operable to contact the test member when the dosing member is to be moved into contact with the test member and to provide up to a predetermined amount of at least a part of the sample to be applied to the test member.

11. A method of testing a sample to detect the presence of a target, the method comprising: applying a sample to be tested to a dosing member; moving the dosing member into contact with a test member, which test member has a visually detectable indicator responsive to the target; and moving the dosing member out of contact with the test member, whereby up to a predetermined amount of at least apart of the sample is applied to the test member.

12. The method of claim 11, comprising moving the dosing member into contact with test member and then out of contact with the test member in response to operation of a moveable member.

13. The method of claim 12, comprising providing access to the dosing member for receipt of the sample in a first position of the moveable member, and preventing access to the dosing member in a second position of the moveable member.

14. The method of claim 13, comprising cam formations of the moveable member and a dosing mechanism carrying the dosing member mutually interoperating to cause the dosing member to be moved in response to movement of the moveable member.

15. The method of claim 14, wherein the cam formations enable movement of the moveable member in a first direction with respect to the housing and resist movement of the moveable member in a direction opposite to the first direction with respect to the housing.

16. The method of any of claims 13 to 15, wherein the dosing member is moved into contact with test member and then moved out of contact with the test member during movement of the moveable member between the first and second positions.

17. The method of any of claims 11 to 15, comprising a first layer of the dosing member receiving the sample and a second layer of the dosing member contacting the test member when the dosing member is moved into contact with the test member to provide up to the predetermined amount of at least a part of the sample to be applied to the test member.