PoC test system and method

Abstract

The present invention relates to a test system or an assay system (detection system) and test method preferably for use in the Point-of-Care (PoC) field.

Claims

1. A test cassette for the detection of at least one analyte from a sample fluid, the test cassette having a first sample chamber and a second sample chamber, which are separated by a carrier having at least two surfaces comprising a front side and a rear side, wherein the front side of the carrier points towards the first sample chamber and the rear side of the carrier points towards the second sample chamber, and a) at least one receptor molecule fixed on the front side of the carrier, b) at least one free volume formed over each of the front side and the rear side of the carrier and delimiting the free volume in each case by a chamber wall, c) the first sample chamber having at least a first opening and a second opening, whereby the sample fluid flows through the first opening along a flow gradient over the front side of the carrier to the second opening distanced from the carrier, d) the second sample chamber having at least a first opening and a second opening, whereby the sample fluid flows through the second sample chamber first opening from the first sample chamber second opening along a flow gradient over the rear side of the carrier, e) the second opening of the first sample chamber and the first opening of the second sample chamber being interconnected by a channel, f) the second opening of the second sample chamber enabling a discharge of the fluid, g) the free volumes from b.) being formed at least partially with a fluid column; and h) the flow gradient flowing along the front side and the rear side of the carrier by means of pressure application and entraining the fluid column from g.).

2. The test cassette according to claim 1, wherein the carrier is partially permeable to a sample fluid.

3. The test cassette according to claim 1, wherein the channel is smaller in diameter than the diameter of the first sample chamber and the second sample chamber or of the free volume over the front side and the rear side of the carrier.

4. The test cassette according to claim 1, wherein the channel surrounds a fastening element of the carrier with the channel having a round bore.

5. The test cassette according to claim 1, including a third chamber fluidly connected to the second opening of the second sample chamber by a further channel, wherein the discharge from the second sample chamber can flow through the further channel to the third chamber, wherein this third chamber a) partially contains an absorbent material and b) contains a vent, Including a third chamber fluidly connected to the second opening of the second sample chamber by a further channel.

6. The test cassette according to claim 1, wherein the test cassette includes three injection moulded components comprising an upper half-shell and a middle part and a lower half-shell, at least one film is located between at least one of the upper half-shell or the lower half-shell and the middle part, the middle part having at least one cutout and least two tabs for receiving the carrier, a further film located between the middle part and the other of the upper half-shell and the lower half-shell, and the three components are interconnected by laser welding.

7. The test cassette according to claim 1, wherein the distance of the front or rear side of the carrier to the chamber wall is at least 10 μm.

8. The test cassette according to claim 7, wherein the distance is 80 μm to 350 μm.

9. The test cassette according to claim 1, wherein the carrier consists of a solid material, completely or partially formed of a gel, porous, sieve, permeable or semi-permeable membrane.

10. The test cassette according to claim 1, wherein at least one receptor molecule is fixed the rear side of a carrier.

11. The test cassette according to claim 1, wherein the flow gradient is guided a.) in parallel on the first and second surface of the carrier or is guided b.) in antiparallel on the first and second surface of the carrier.

12. The test cassette according to claim 1, characterised in that the pressure application occurs by means of overpressure or negative pressure.

13. The test cassette according to claim 1, characterised in that the carrier has a length of 40-60 mm, a width of 2.0-10 mm, and an inlet diameter of 0.15 to 0.45 mm.

14. The test cassette according to claim 1, characterised in that the first and second sample chambers are part of a plurality of more than two sample chambers.

15. The test cassette according to claim 4, wherein the fastening element is a transverse strut.

16. The test cassette according to claim 5, wherein the vent is an additional channel with at least one bend or at least one additional chamber.

17. The test cassette according to claim 7, wherein the distance is up to 1,500 μm.

18. The test cassette according to claim 8, wherein the distance is 120 μm to 200 μm, and there are different distances of the front side and the rear side of the carrier.

Description

EXAMPLES AND FIGURES

(1) These examples serve exclusively for explanation of the invention and do not limit the invention to these examples.

Example 1

Test Protocol for Allergy Test

(2) Preparation

(3) Bring test box with test tubes and test cassette (kit containing sample chamber) and also the patient sample to room temperature (18-25° C.)

(4) Have ready timer, disposable gloves, container for solid waste and pen.

(5) Remove test cassette and syringe.

(6) All incubations take place at room temperature.

(7) Reinsert, upright, the reagent tubes inserted in the test box (kit), either prior to or following the test procedure, into the correspondingly coloured holding devices at the upper edge of the box.

(8) 1.1. Sample Introduction:

(9) Open sample tubes (red cover) containing previously introduced sample and transfer the content completely and bubble-free into the test cassette by means of the syringe. For this purpose insert the syringe into the sample opening and inject the content quickly.

(10) Set down the test cassette on a flat support and incubate for 4 minutes.

(11) 1.2. Addition of the Test Solution:

(12) Quickly inject the content of the conjugate solution (yellow cover) as described before (section 10.1.) into the inlet of the test cassette with the aid of the syringe and incubate this, set down, for 8 minutes.

(13) 1.3. Washing:

(14) Open the first test tube containing washing solution (blue cover) and quickly inject the content as previously described into the inlet of the test cassette. Then immediately quickly inject the content of the second test tube containing washing solution (blue cover). No incubation is necessary.

(15) 1.4. Development:

(16) Open the first tube containing colour substrate (white cover) and quickly inject the content into the inlet of the test cassette. Then immediately open the second test tube containing colour substrate (white cover), inject the content bubble-free into the inlet of the test cassette and incubate this, set down, for 8 minutes.

(17) During the development, 2 parallel reference lines of different intensity and possibly additionally a central test: line are visible in each test field.

(18) 1.5. Stopping:

(19) Open test tubes containing stop solution (green cover) and inject the content into the inlet of the test cassette. Note: The test results are stable for at least 12 hours and can be read off during this time.

Example 2

Test Chamber (Sample Chamber)

(20) Dimensions for the membrane and values of the distances thereof from other elements of the device will be specified hereinafter. Here, it should be noted that all dimensions/values are specified for the dry state of the membrane and that a possible deflection of the membrane or surface unevennesses or a potential warping of the injection-moulded parts is not taken into consideration. In the moist state the membrane may swell or deflect and may thus have a modified thickness and modified distances from other components.

(21) A (reinforced) nitrocellulose membrane 140 μm thick is cut to a size of 50.5 mm×6.3 mm. The resultant membrane strip is placed on a film provided with a cutout, such that the strip completely covers the cutout and is clamped at the end sides thereof in each case beneath a tab, said tabs being located at the end-side ends of the cutout in the film. The film is clamped with the membrane strip between two injection-moulded half-shells, which together with the film and the membrane strip form both sample chambers according to FIGS. 1b and 2, of which the width is 3.5 mm. The total volume of the membrane is thus 44.5 μl, and that of the free membrane is 24.7 μl. The distance of the membrane upper side to the substantially planar inner side of the upper chamber wall is 170 μm, and that from the membrane lower side to the substantially planar lower chamber wall of the half-shell is 150 μm. The volume of the upper chamber is 30.04 μl, and that of the lower chamber is 26.51 μl. The cross section of the unclamped part of the membrane is 0.49 mm.sup.2, and that of the chamber is 1.62 mm.sup.2.

(22) The chamber is provided with an inlet opening in the first sample chamber in the vicinity of an end of the membrane, which inlet opening has a cross section of 0.3 mm.sup.2, and with an outlet opening in the second sample chamber in the vicinity of the membrane with a cross section of 1.2 mm.sup.2.

(23) In the test device 4×2 chambers are formed in parallel, such that the entire membrane volume is 98.98 μl, that of the first chambers without inflow and outflow is 120.19 μl, and that of the second chambers is 106.05 μl. They are filled simultaneously through a single access (sample channel), which fans out into 4 channels, each of which is connected to a first chamber. The outlet openings in turn converge into a single channel, which is connected to a waste volume integrated in the test device, in which waste volume absorbent material is accommodated. The absorbent material is not fluidically connected to any membrane, and therefore the suction effect is limited to free fluid that passes into the waste. The test device has windows, through which the regions of the test strips charged with reagent can be observed.

(24) An opaque film provided with cutouts is bonded to the test cassette. The cutouts serve as windows, through each of which windows the measuring fields each provided for a respective allergen can be viewed or read out using an optical reader. The webs between the windows, which are lined up along a carrier, are kept as narrow as possible, for example 2 mm or less. The webs perpendicularly thereto, from carrier to carrier are wider, such that there is enough space thereon for printed-out information regarding the individual measuring fields. This information may include numbers, acronyms or an entire term, for example designating the allergen.

(25) In a test the following substances and quantities are added in the test device in accordance with protocol 1:

(26) TABLE-US-00001 1) sample together with sample diluent 380 μl 2) washing bugger per procedure 1,000 μl 3) substrate solution per procedure (flushing twice) 2 × 800 μl 4) antibody/conjugate solution 1 800 μl 5) antibody/conjugate solution 2 800 μl 6) stop buffer 1,000 μl

(27) The volume of each individual test component is greater than the volume of the membranes (100 μl).

DESCRIPTION OF THE FIGURES

(28) FIG. 1a: longitudinal section through a test cassette with both sample chambers, in which fluid is guided at both surfaces of the carrier (1) (front side and rear side) in the flow (3) in parallel. The cassette is pressurised through the inlet opening (5), such that the fluid flows from there to the outlet opening and from there through a further channel to the waste (4) (auxiliary chamber (supra)).

(29) FIG. 1b: longitudinal section through a sample chamber, in which fluid flows at the end of the carrier (1) through a further channel and is conveyed to the rear side of the carrier and flows at the second surface (rear side) antiparallel to the first surface.

(30) FIG. 2: Plan view of a sample chamber. A number of carriers may be arranged in parallel in a cassette. For this purpose, the flow may be divided or the carriers may be located jointly in one cavity.

(31) FIG. 3: Detailed longitudinal section of an embodiment, not shown to scale. The solutions are introduced through the inlet opening (5) and flow (3) over the front side of the fixed carrier (1), on which test reagents (2) are located. From there, the solutions pass via a further channel at the other end of the carrier to the rear side of the carrier and flow over this to an outlet opening. An additional channel conveys the fluids to the waste (4), which preferably contains an absorbent material. The chamber for the waste is connected to the outside world via a vent. This vent may be provided with a chicane and further chambers, so as to prevent a leakage of the waste.

(32) FIG. 4: Immunoassay with three identical membranes as solid phase, performed at the same time in accordance with the protocol from Example 1. In tracks 1 and 2 fluid flows over the membranes from both sides, and in track 3 fluid flows over the upper side only. Identical reagents and volumes were used in all tracks.

(33) FIG. 5: Longitudinal section as exploded drawing to illustrate the layered structure of the test cassette. The films are located in each case between an injection-moulded half-shell, which is transparent in some regions, and a middle part, which likewise is injection moulded. The laser welds, through the half-shells, the film to the half-shell and middle part, and also welds the half-shells and middle part to one another.

(34) FIG. 6: Detailed plan view of the carrier, not true to scale. The carrier is clamped beneath the end-side tabs of the film and covers the cutout in the film

(35) FIG. 7: Cross section through a test cassette, not true to scale. The carrier is fixed at the edges of the sample chambers. Any curvature of the carrier in the transverse direction is shown heavily exaggerated. If a curvature is present or is produced after wetting, the carrier is preferably inserted such that the curvature is formed towards the front side.