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LIQUID HANDLING DEVICE

20230147248 · 2023-05-11

    Inventors

    Cpc classification

    International classification

    Abstract

    The present disclosure relates to a liquid handling device, methods of operating a liquid handling device, a method of performing a diagnostic test, a computer program and a system. In particular, the liquid handling device is capable of controllable bi-directional or multi-directional flow of reagents across one or more reaction zones allowing rapid, precise and controllable quenching of reactions and/or biological interactions.

    Claims

    1. A liquid handling device comprising: a sample chamber for receiving a sample; a measurement chamber for performing one or more measurements on the sample wherein the measurement chamber comprises a reaction zone; a first liquid reagent chamber; a sample chamber conduit which fluidically connects the sample chamber to the measurement chamber; a sample chamber conduit valve for opening and closing the sample chamber conduit; a first liquid reagent chamber conduit which fluidically connects the first liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample chamber conduit; and a first liquid reagent chamber conduit valve for opening and closing the first liquid reagent chamber conduit.

    2. The liquid handling device of claim 1 wherein the flow direction of the first liquid reagent chamber conduit is at least ninety degrees to the flow direction of the sample chamber conduit, preferably wherein the flow direction of the first liquid reagent chamber conduit is opposite to the flow direction of the sample chamber conduit.

    3. The liquid handling device of any previous claim, wherein the device further comprises: a second liquid reagent chamber; a second liquid reagent chamber conduit which fluidically connects the second liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample chamber conduit; and a second liquid reagent chamber conduit valve for opening and closing the second liquid reagent chamber conduit.

    4. The liquid handling device of claim 3 wherein the second liquid reagent chamber conduit fluidically connects to the measurement chamber in an alternate direction to both the sample chamber conduit and the first liquid reagent chamber conduit.

    5. The liquid handling device of claim 3 wherein the second liquid reagent chamber conduit is fluidically connected to the first liquid reagent chamber conduit thereby providing a combined conduit, fluidically connecting both the first liquid reagent chamber and second liquid reagent chamber to the measurement chamber.

    6. The liquid handling device of claim 5 wherein the flow direction of the combined conduit into the measurement chamber is at least ninety degrees to the flow direction of the sample chamber conduit into the measurement chamber.

    7. The liquid handling device of claim 5 or 6 wherein the flow direction of the combined conduit into the measurement chamber is opposite to the flow direction of the sample chamber conduit into the measurement chamber.

    8. The liquid handling device of claim 4 wherein the flow direction of the second liquid reagent chamber conduit into the measurement chamber is at least ninety degrees to the flow direction of the sample chamber conduit and/or the first liquid chamber conduit into the measurement chamber.

    9. The liquid handling device of claim 8 wherein the flow direction of the second liquid reagent chamber conduit into the measurement chamber is opposite to the flow direction of the sample chamber conduit and/or the first liquid chamber conduit into the measurement chamber.

    10. The liquid handling device of any previous claim wherein the device comprises two or more measurement chambers, each of which is fluidically connected to the sample chamber and each of which is fluidically connected to the first liquid reagent chamber, wherein the device comprises a corresponding number of sample chamber conduit valves and/or first liquid reagent chamber valves for independent control of the flow of sample liquid and/or first liquid reagent into each measurement chamber.

    11. The liquid handling device of claim 10, wherein the device further comprises a second liquid reagent chamber and wherein each of the measurement chambers is fluidically connected to the second liquid reagent chamber, and wherein the device comprises a corresponding number of second liquid reagent chamber conduit valves for independent control of the flow of second liquid reagent into each measurement chamber.

    12. The liquid handling device of claim 11, wherein the second liquid reagent chamber conduit is fluidically connected to the first liquid reagent chamber conduit thereby providing one or more combined conduits fluidically connecting both the first liquid reagent chamber and second liquid reagent chamber to each measurement chamber.

    13. The liquid handling device of any previous claim, wherein the flow of any one or more of the sample liquid, first liquid reagent and/or the second liquid reagent into each of the measurement chambers can be independently controlled to regulate the residence time of each liquid in each of the measurement chambers.

    14. The liquid handling device of claim 13 wherein the flow of any one or more of the sample liquid, first liquid reagent and/or the second liquid reagent is controlled such that the residence time of each liquid is a predetermined period of time.

    15. The liquid handling device of any previous claim, wherein the device further comprises: a mixing zone located between the sample chamber and the measurement chamber and wherein the mixing zone is fluidically connected to both the sample chamber and the measurement chamber.

    16. The liquid handling device of claim 15, wherein the mixing zone comprises a mixing chamber, wherein the mixing chamber is fluidically connected to the sample chamber conduit and to the measurement chamber by a mixing chamber conduit.

    17. The liquid handling device of any one of claim 15 or 16 wherein the device further comprises: a third liquid reagent chamber; a third liquid reagent chamber conduit which fluidically connects the third liquid reagent chamber to the mixing zone, optionally wherein the third liquid reagent chamber conduit connects to the mixing zone in an alternate flow direction to the sample chamber conduit; and a third liquid reagent chamber conduit valve for opening and closing the third liquid reagent chamber conduit.

    18. A method of performing a diagnostic assay comprising sequentially moving liquid from a sample chamber to a measurement chamber and moving a first liquid reagent into the measurement chamber from an alternate flow direction, the method including: filling the sample chamber with sample liquid; moving sample liquid from the sample chamber to the measurement chamber; retaining the sample liquid in the measurement chamber for a predetermined period of time, moving a first liquid reagent from a first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample chamber liquid and taking a measurement, optionally wherein the first liquid reagent is retained in the measurement chamber for a predetermined period of time.

    19. The method of claim 18 wherein the first liquid reagent is removed from the measurement chamber before the measurement is taken.

    20. The method of claim 18 or claim 19, further comprising a step of moving liquid from a second liquid reagent chamber to the measurement chamber in an alternate flow direction to sample liquid.

    21. A method of performing a diagnostic assay comprising sequentially moving liquid from a sample chamber to a measurement chamber and moving a first and second liquid reagent into the measurement chamber from an alternate flow direction, the method including: filling the sample chamber with sample liquid; moving sample liquid from the sample chamber to the measurement chamber; retaining the sample liquid in the measurement chamber for a predetermined period of time, moving a first liquid reagent from a first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid; moving a second liquid reagent from a second liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid and performing a measurement, optionally wherein the first and second liquid reagents are each retained in the measurement chamber for a predetermined period of time.

    22. The method of claim 21 wherein the second liquid reagent is removed from the measurement chamber before the measurement is taken.

    23. A method of performing a diagnostic assay comprising sequentially moving liquid from a sample chamber to a measurement chamber and moving a first and second liquid reagent into the measurement chamber from an alternate flow direction, the method including: filling the sample chamber with sample liquid; moving sample liquid from the sample chamber to the measurement chamber; retaining the sample liquid in the measurement chamber for a predetermined period of time, moving a first liquid reagent from a first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid; moving a second liquid reagent from a second liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid; moving a further volume of the first liquid reagent from the first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid and performing a measurement, optionally wherein the first and second liquid reagents are each retained in the measurement chamber for a predetermined period of time.

    24. The method of any one of claims 18-23 wherein the flow direction of the first liquid reagent and/or the second liquid reagent is at least ninety degrees to the flow direction of the sample liquid into the measurement chamber, preferably wherein the flow direction of the first liquid reagent and/or second liquid reagent is opposite to the flow direction of the sample liquid.

    25. A method of implementing the method described in any one of claims 18-24 on a device of any one of claims 1-17.

    Description

    BRIEF DESCRIPTION OF THE DRAWINGS

    [0095] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

    [0096] FIG. 1A illustrates a liquid handling device comprising a sample chamber, a measurement chamber and a first liquid reagent chamber fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber.

    [0097] FIG. 1B illustrates a liquid handling device comprising a sample chamber, a measurement chamber and a first liquid reagent chamber fluidically connected to the measurement chamber in an alternate flow direction. This alternative configuration illustrates that the flow direction of the first liquid reagent chamber conduit into the measurement chamber can be at ninety degrees to the flow direction of the sample chamber conduit.

    [0098] FIG. 2A illustrates a liquid handling device comprising a sample chamber, a measurement chamber and a first liquid reagent chamber and second liquid reagent chamber, both fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber.

    [0099] FIG. 2B illustrates a liquid handling device comprising a sample chamber, a measurement chamber and a first liquid reagent chamber and second liquid reagent chamber, both fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber. This alternative configuration illustrates that the flow direction of the first liquid reagent chamber conduit and second liquid reagent chamber conduit into the measurement chamber can be at ninety degrees to the flow direction of the sample chamber conduit and/or at ninety degrees to the flow direction of the other liquid reagent chamber conduit.

    [0100] FIG. 2C illustrates a liquid handling device comprising a sample chamber, a measurement chamber and a first liquid reagent chamber and second liquid reagent chamber, both fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber. This alternative configuration illustrates that the first liquid reagent chamber conduit and second liquid reagent chamber conduit can be joined to provide a single combined conduit, connected to the measurement chamber in an alternate flow direction to the sample chamber.

    [0101] FIG. 3 illustrates a liquid handling device comprising a sample chamber, multiple measurement chambers and a first liquid reagent chamber, fluidically connected to each measurement chamber in an alternate flow direction to the sample chamber. Flow from both the sample chamber and first liquid reagent chamber is independently controllable into each measurement chamber.

    [0102] FIG. 4A illustrates a liquid handling device comprising a sample chamber, multiple measurement chambers and a first liquid reagent chamber and second liquid reagent chamber, both fluidically connected to each measurement chamber in an alternate flow direction to the sample chamber. Flow from each of the sample chamber, first liquid reagent chamber and second liquid reagent chamber is independently controllable into each measurement chamber.

    [0103] FIG. 4B illustrates a liquid handling device comprising a sample chamber, multiple measurement chambers and a first liquid reagent chamber and second liquid reagent chamber, both fluidically connected to each measurement chamber in an alternate flow direction to the sample chamber. Flow from each of the sample chamber, first liquid reagent chamber and second liquid reagent chamber is independently controllable into each measurement chamber. This alternative configuration illustrates that the first liquid reagent chamber conduit and second liquid reagent chamber conduit can be joined to provide a single combined conduit, connected to each measurement chamber in an alternate flow direction to the sample chamber.

    [0104] FIG. 5A illustrates a liquid handling device according to FIG. 1 comprising a sample chamber, a mixing zone, a measurement chamber and a first liquid reagent chamber fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber.

    [0105] FIG. 5B illustrates a liquid handling device according to FIG. 1 comprising a sample chamber, a mixing zone, a measurement chamber, a first liquid reagent chamber fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber and a third liquid reagent chamber fluidically connected to the mixing zone in an alternate flow direction to the sample chamber.

    [0106] FIG. 6 illustrates a liquid handling device comprising a sample chamber, a mixing zone, a measurement chamber, and a first liquid reagent chamber and second liquid reagent chamber, both fluidically connected to the measurement chamber in an alternate flow direction to the sample chamber and a third liquid reagent chamber fluidically connected to the mixing zone in an alternate flow direction to the sample chamber. This configuration illustrates that the first liquid reagent chamber conduit and second liquid reagent chamber conduit can be joined to provide a single combined conduit, connected to the measurement chamber in an alternate flow direction to the sample chamber. Alternatively, the device of FIG. 6 may comprise a separate first liquid reagent chamber conduit and second liquid reagent chamber conduit.

    [0107] FIG. 7 illustrates a flow diagram for a method of operating a liquid handling device comprising a sample chamber, a measurement chamber and a first liquid reagent chamber.

    [0108] FIG. 8 illustrates a flow diagram for a method of operating a liquid handling device comprising a sample chamber, a measurement chamber, a first liquid reagent chamber and a second liquid reagent chamber.

    [0109] FIG. 9 illustrates a flow diagram for an alternative method of operating a liquid handling device comprising a sample chamber, a measurement chamber, a first liquid reagent chamber and a second liquid reagent chamber.

    [0110] FIG. 10 illustrates the novel design comprising an assay workflow that introduces reagents through both port A and port B.

    [0111] FIG. 11A illustrates D-Dimer assay performance compared to a control manual method when adding reagents from both directions.

    [0112] FIG. 11B illustrates D-Dimer assay performance compared to a control manual method when adding all reagents from one direction.

    [0113] FIG. 12 illustrates D-Dimer assay performance, as measured by signal to control ratio, directly comparing a unidirectional flow configuration to a bidirectional flow configuration. The signal to control ratio is higher when using a bidirectional flow configuration, which indicates better assay performance.

    [0114] FIG. 13 illustrates peak current versus concentration over a concentration range for the D-Dimer assay using a bidirectional flow configuration and a control configuration.

    DETAILED DESCRIPTION OF THE INVENTION

    [0115] FIG. 1A illustrates a liquid handling device 100. The liquid handling device 100 comprises a sample chamber 102 for receiving a sample; one or more measurement chambers 104 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 114; a sample chamber conduit 112 which fluidically connects the sample chamber 102 to the measurement chamber 104; a sample chamber conduit valve 122 for opening and closing the sample chamber conduit 112; a first liquid reagent chamber 106; a first liquid reagent chamber conduit 116 which fluidically connects the first liquid reagent chamber 106 to the measurement chamber 104 in an alternate flow direction to the sample chamber conduit 112; and a first liquid reagent chamber conduit valve 126 for opening and closing the first liquid reagent chamber conduit 116. In the embodiment shown in FIG. 1A, the first liquid reagent chamber conduit 116 connects to the measurement chamber 104 in the opposite flow direction to the sample chamber conduit 112.

    [0116] The measurement chamber 104 is arranged to receive a fluid from the sample chamber 102 when the sample chamber conduit valve 122 is open and a negative pressure change is applied to the measurement chamber 104.

    [0117] The measurement chamber 104 comprises a reaction zone 114, optionally comprising a plurality of electrodes (not illustrated in FIG. 1).

    [0118] FIG. 1B illustrates a liquid handling device 100 similar to the device illustrated in FIG. 1A, wherein the first liquid reagent chamber conduit 113, enters the measurement chamber 104 in an alternate flow direction to the sample chamber conduit 112. The liquid handling device 100 comprises a sample chamber 102 for receiving a sample; one or more measurement chambers 104 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 114; a sample chamber conduit 112 which fluidically connects the sample chamber 102 to the measurement chamber 104; a sample chamber conduit valve 122 for opening and closing the sample chamber conduit 112; a first liquid reagent chamber 103; a first liquid reagent chamber conduit 113 which fluidically connects the first liquid reagent chamber 103 to the measurement chamber 104 in an alternate flow direction to the sample chamber conduit 112; and a first liquid reagent chamber conduit valve 123 for opening and closing the first liquid reagent chamber conduit 113. In the embodiment shown in FIG. 1B, the first liquid reagent chamber conduit 113 connects to the measurement chamber 104 with a flow direction that is 90 degrees to the flow direction of the sample chamber conduit 112, in the same horizontal plane of the device.

    [0119] FIG. 2A illustrates a liquid handling device 200 similar to the devices illustrated in FIG. 1A and FIG. 1B, further comprising a second fluid reagent chamber. The liquid handling device 200 comprises a sample chamber 202 for receiving a sample; one or more measurement chambers 204 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 214; a sample chamber conduit 212 which fluidically connects the sample chamber 202 to the measurement chamber 204; a sample chamber conduit valve 222 for opening and closing the sample chamber conduit 212; a first liquid reagent chamber 206; a first liquid reagent chamber conduit 216 which fluidically connects the first liquid reagent chamber 206 to the measurement chamber 204 in an alternate flow direction to the sample chamber conduit 212; a first liquid reagent chamber conduit valve 226 for opening and closing the first liquid reagent chamber conduit 216; a second liquid reagent chamber 203; a second liquid reagent chamber conduit 213 which fluidically connects the second liquid reagent chamber 203 to the measurement chamber 204 in an alternate flow direction to the sample chamber conduit 212; and a second liquid reagent chamber conduit valve 223 for opening and closing the second liquid reagent chamber conduit 223. In the embodiment shown in FIG. 2A, the first liquid reagent chamber conduit 216 and the second liquid reagent chamber conduit 213 connects to the measurement chamber 204 in the opposite flow direction to the sample chamber conduit 212.

    [0120] FIG. 2B illustrates a liquid handling device 200 similar to the device illustrated in FIG. 2A, wherein the second liquid reagent chamber conduit 213, enters the measurement chamber 204 in an alternate flow direction to both the sample chamber conduit 212 and the first liquid reagent chamber conduit 216. The liquid handling device 200 comprises a sample chamber 202 for receiving a sample; one or more measurement chambers 204 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 214; a sample chamber conduit 212 which fluidically connects the sample chamber 202 to the measurement chamber 204; a sample chamber conduit valve 222 for opening and closing the sample chamber conduit 212; a first liquid reagent chamber 206; a first liquid reagent chamber conduit 216 which fluidically connects the first liquid reagent chamber 206 to the measurement chamber 204 in an alternate flow direction to the sample chamber conduit 212; a first liquid reagent chamber conduit valve 226 for opening and closing the first liquid reagent chamber conduit 216; a second liquid reagent chamber 203; a second liquid reagent chamber conduit 213 which fluidically connects the second liquid reagent chamber 203 to the measurement chamber 204 in an alternate flow direction to the sample chamber conduit 212; and a second liquid reagent chamber conduit valve 223 for opening and closing the second liquid reagent chamber conduit 223. In the embodiment shown in FIG. 2B, the first liquid reagent chamber conduit 216 connects to the measurement chamber 204 in the opposite flow direction to the sample chamber conduit 212 and the second liquid reagent chamber conduit connects to the measurement chamber at an alternate angle (e.g. ninety degrees) to both the sample chamber conduit 212 and the first liquid reagent chamber conduit 216.

    [0121] FIG. 2C illustrates a liquid handling device 200 similar to the device illustrated in FIG. 2A, wherein the first liquid reagent chamber conduit 216 and the second liquid reagent chamber conduit 213 are joined to form a combined conduit which enters the measurement chamber 204 in an alternate flow direction to the sample chamber conduit 212. The liquid handling device 200 comprises a sample chamber 202 for receiving a sample; one or more measurement chambers 204 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 214; a sample chamber conduit 212 which fluidically connects the sample chamber 202 to the measurement chamber 204; a sample chamber conduit valve 222 for opening and closing the sample chamber conduit 212; a first liquid reagent chamber 206; a first liquid reagent chamber conduit 216; a first liquid reagent chamber conduit valve 226 for opening and closing the first liquid reagent chamber conduit 216; a second liquid reagent chamber 203; a second liquid reagent chamber conduit 213; a second liquid reagent chamber conduit valve 223 for opening and closing the second liquid reagent chamber conduit 223, wherein the first liquid reagent chamber conduit 216 and the second liquid reagent chamber conduit 213 are joined to form a combined conduit which fluidically connects both reagent chamber conduits to the measurement chamber 204 in an alternate flow direction to the sample chamber conduit 212. In the embodiment shown in FIG. 2B, the combined conduit connects to the measurement chamber 204 in the opposite flow direction to the sample chamber conduit 212.

    [0122] FIG. 3 illustrates a liquid handling device 300 similar to the devices illustrated in FIGS. 1A and 1B, wherein the device comprises multiple measurement chambers. The liquid handling device 300 comprises a sample chamber 302 for receiving a sample; multiple measurement chambers 304a/304b/304c for performing measurements on the sample, wherein the measurement chambers optionally comprise a reaction zone (not shown in FIG. 3); a sample chamber conduit 312a/312b/312c which independently fluidically connects the sample chamber 302 to each of the measurement chambers 304a/304b/304c; a corresponding number of sample chamber conduit valves 322a/322b/322c for opening and closing the sample chamber conduit 312a/312b/312c; a first liquid reagent chamber 306; a first liquid reagent chamber conduit 316a/316b/316c which independently fluidically connects the first liquid reagent chamber 306 to each of the measurement chambers 304a/304b/304c in an alternate flow direction to the sample chamber conduit 312a/312b/312c; and a corresponding number of first liquid reagent chamber conduit valves 326a/326b/326c for opening and closing the first liquid reagent chamber conduit 316a/316b/316c. The sample chamber conduit valves 322a/322b/322c and first liquid reagent chamber conduit valves 326a/326b/326c allow for independent control of sample liquid and/or first liquid reagent in each of the measurement chambers.

    [0123] FIG. 4A illustrates a liquid handling device 400 similar to the devices illustrated in FIG. 2A and FIG. 3, comprising a second fluid reagent chamber. The liquid handling device 400 comprises a sample chamber 402 for receiving a sample; multiple measurement chambers 404a/404b/404c for performing measurements on the sample, wherein the measurement chambers optionally comprise a reaction zone (not shown in FIG. 4A); a sample chamber conduit 412a/412b/412c which fluidically connects the sample chamber 402 to each measurement chamber 404a/404b/404c; a corresponding number of sample chamber conduit valves 422a/422b/422c for opening and closing the sample chamber conduit 412a/412b/412c; a first liquid reagent chamber 406; a first liquid reagent chamber conduit 416a/416b/416c which fluidically connects the first liquid reagent chamber 406 to each measurement chamber 404a/404b/404c in an alternate flow direction to the sample chamber conduit 412a/412b/412c; a corresponding number of first liquid reagent chamber conduit valves 426a/426b/426c for opening and closing the first liquid reagent chamber conduit 416a/416b/416c; a second liquid reagent chamber 408; a second liquid reagent chamber conduit 436a/436b/436c which fluidically connects the second liquid reagent chamber 408 to each measurement chamber 404a/404b/404c in an alternate flow direction to the sample chamber conduit 412a/412b/412c; and a corresponding number of second liquid reagent chamber conduit valves 446a/446b/446c for opening and closing the second liquid reagent chamber conduit 436a/436b/436c. In the embodiment shown in FIG. 4A, the first liquid reagent chamber conduit 416a/416b/416c and the second liquid reagent chamber conduit 436a/436b/436c connects to each measurement chamber 404a/404b/404c in the opposite flow direction to the sample chamber conduit 412a/412b/412c. In an alternative configuration, the first liquid reagent chamber conduit 416a/416b/416c and the second liquid reagent chamber conduit 436a/436b/436c can connect to each measurement chamber 404a/404b/404c at different flow directions, both of which may be alternative flow directions to the sample chamber conduit 412a/412b/412c.

    [0124] FIG. 4B illustrates a liquid handling device 400 similar to the device illustrated in FIG. 4A, wherein the first liquid reagent conduit and the second liquid reagent conduit are joined to form a combined conduit that connects both chambers to each measurement chamber. The liquid handling device 400 comprises a sample chamber 402 for receiving a sample; multiple measurement chambers 404a/404b/404c for performing measurements on the sample, wherein the measurement chambers optionally comprise a reaction zone (not shown in FIG. 4A); a sample chamber conduit 412a/412b/412c which fluidically connects the sample chamber 402 to each measurement chamber 404a/404b/404c; a corresponding number of sample chamber conduit valves 422a/422b/422c for opening and closing the sample chamber conduit 412a/412b/412c; a first liquid reagent chamber 406; a first liquid reagent chamber conduit valve 446 for opening and closing the first liquid reagent chamber conduit 436; a second liquid reagent chamber 408; a second liquid reagent chamber conduit valve 448 for opening and closing the second liquid reagent chamber conduit 436, a combined conduit 432 which is fluidically connected to both the first liquid reagent conduit 436 and the second liquid reagent conduit 438, wherein the combined conduit is fluidically connected to each measurement chamber 404a/404b/404c in an alternate flow direction to the sample chamber conduit 412a/412b/412c. In the embodiment shown in FIG. 4B, the combined conduit 432 connects to each measurement chamber 404a/404b/404c in the opposite flow direction to the sample chamber conduit 412a/412b/412c. In an alternative configuration, the combined conduit 432 can connect to each measurement chamber 404a/404b/404c at an alternative flow direction (such as ninety degrees) to the sample chamber conduit 412a/412b/412c.

    [0125] FIG. 5A illustrates a liquid handling device 500 similar to the device illustrated in FIG. 1A, further comprising a mixing zone 508. The liquid handling device 500 comprises a sample chamber 502 for receiving a sample; a mixing zone 508, one or more measurement chambers 504 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 514; a sample chamber conduit 512 which fluidically connects the sample chamber 502 to the mixing chamber 508; a sample chamber conduit valve 522 for opening and closing the sample chamber conduit 512; a mixing chamber conduit 518 which fluidically connects the mixing chamber 508 to the measurement chamber 504; a first liquid reagent chamber 506; a first liquid reagent chamber conduit 516 which fluidically connects the first liquid reagent chamber 506 to the measurement chamber 504 in an alternate flow direction to the sample chamber conduit 512; and a first liquid reagent chamber conduit valve 526 for opening and closing the first liquid reagent chamber conduit 516. In the embodiment shown in FIG. 5A, the first liquid reagent chamber conduit 516 connects to the measurement chamber 504 in the opposite flow direction to the mixing chamber conduit 518.

    [0126] FIG. 5B illustrates a liquid handling device 500 similar to the device illustrated in FIG. 1B, further comprising a mixing zone 508 and a third liquid reagent chamber 505. The liquid handling device 500 comprises a sample chamber 502 for receiving a sample; a mixing zone 508, one or more measurement chambers 504 for performing measurements on the sample, wherein the measurement chamber comprises a reaction zone 514; a sample chamber conduit 512 which fluidically connects the sample chamber 502 to the mixing chamber 508; a sample chamber conduit valve 522 for opening and closing the sample chamber conduit 512; a mixing chamber conduit 518 which fluidically connects the mixing chamber 508 to the measurement chamber 504; a first liquid reagent chamber 506; a first liquid reagent chamber conduit 516 which fluidically connects the first liquid reagent chamber 506 to the measurement chamber 504 in an alternate flow direction to the sample chamber conduit 512; a first liquid reagent chamber conduit valve 526 for opening and closing the first liquid reagent chamber conduit 516; a third liquid reagent chamber 505; a third liquid reagent chamber conduit 515 which fluidically connects the third liquid reagent chamber 505 to the mixing chamber 508; and a third liquid reagent chamber conduit valve 525 for opening and closing the third liquid reagent chamber conduit 515. In the embodiment shown in FIG. 5B, the first liquid reagent chamber conduit 516 connects to the measurement chamber 504 in the opposite flow direction to the mixing chamber conduit 518. In the embodiment shown in FIG. 5B, the third liquid reagent chamber conduit 515 connects to the mixing chamber 508 at an alternative flow direction to the sample chamber conduit 512. In an alternative embodiment the third liquid reagent chamber conduit 515 could join the mixing chamber in the same flow direction as the sample chamber conduit 512.

    [0127] FIG. 6 illustrates a liquid handling device 600 similar to the device illustrated in FIG. 2C and FIG. 5B, further comprising a mixing zone 608, a second liquid reagent chamber 603 and a third liquid reagent chamber 605. The liquid handling device 600 comprises a sample chamber 602 for receiving a sample; a mixing zone 608, one or more measurement chambers 604 for performing measurements on the sample, wherein the measurement chamber comprises one or more reaction zones 614a/614b; a sample chamber conduit 612 which fluidically connects the sample chamber 602 to the mixing chamber 608; a sample chamber conduit valve 622 for opening and closing the sample chamber conduit 612; a mixing chamber conduit 617 which fluidically connects the mixing chamber 608 to the measurement chamber 604; a first liquid reagent chamber 606; a first liquid reagent chamber conduit 616; a first liquid reagent chamber conduit valve 626 for opening and closing the first liquid reagent chamber conduit 616; a second liquid reagent chamber 603; a second liquid reagent chamber conduit 613; a second liquid reagent chamber conduit valve 623 for opening and closing the second liquid reagent chamber conduit 613; wherein the first liquid reagent chamber conduit 616 and the second liquid reagent chamber conduit 613 are joined to form a combined conduit which fluidically connects both reagent chamber conduits to the measurement chamber 604 in an alternate flow direction to the mixing chamber conduit 617; a third liquid reagent chamber 605; a third liquid reagent chamber conduit 615 which fluidically connects the third liquid reagent chamber 605 to the mixing chamber 608; and a third liquid reagent chamber conduit valve 625 for opening and closing the third liquid reagent chamber conduit 615. In the embodiment shown in FIG. 5B, the first liquid reagent chamber conduit and the second liquid reagent chamber are joined to form a combined conduit which connects to the measurement chamber 604 in an alternate flow direction to the mixing chamber conduit 617.

    [0128] FIG. 7 illustrates a flow diagram for a method of operating any of the liquid handling devices 100/200/300/400/500/600 described above and comprising at least a sample chamber 102/202/302/402/502/602, a measurement chamber 104/204/304/404/504/604 and a first liquid reagent chamber 106/206/306/406/506/606. The method is for transferring a sample liquid from the sample chamber to the measurement chamber and then moving a first liquid reagent from the first liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample liquid, then performing a measurement.

    [0129] When a sample has been inserted into the sample chamber 102/202/302/402/502/602 and the first liquid reagent chamber 106/206/306/406/506/606 contains a first liquid reagent, the method achieves the following:

    a) opening the sample chamber conduit valve 122/222/322/422/522/622;
    b) reducing a pressure in the measurement chamber 104/204/304/404/504/604 relative to the sample chamber 102/202/302/402/502/602;
    c) closing the sample chamber conduit valve 122/222/322/422/522/622;
    d) opening the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    e) reducing a pressure in the measurement chamber relative to the first liquid reagent chamber;
    f) closing the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    g) performing a measurement in the measurement chamber.

    [0130] FIG. 8 illustrates a flow diagram for a method of operating any of the liquid handling devices 100/200/300/400/500/600 described above and comprising at least a sample chamber 102/202/302/402/502/602, a measurement chamber 104/204/304/404/504/604, a first liquid reagent chamber 106/206/306/406/506/606 and a second liquid reagent chamber 203/408/603. The method is for transferring a sample liquid from the sample chamber to the measurement chamber, then moving a first liquid reagent from the first liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample liquid, then moving a second liquid reagent from the second liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample liquid (optionally wherein the flow direction of the second liquid reagent is also alternate to the flow direction of the first liquid reagent), and performing a measurement.

    [0131] When a sample has been inserted into the sample chamber 102/202/302/402/502/602, the first liquid reagent chamber 106/206/306/406/506/606 contains a first liquid reagent and the second liquid reagent chamber 203/408/603 contains a second liquid reagent, the method achieves the following:

    a) opening the sample chamber conduit valve 122/222/322/422/522/622;
    b) reducing a pressure in the measurement chamber 104/204/304/404/504/604 relative to the sample chamber 102/202/302/402/502/602;
    c) closing the sample chamber conduit valve 122/222/322/422/522/622;
    d) opening the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    e) reducing a pressure in the measurement chamber relative to the first liquid reagent chamber;
    f) closing the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    g) opening the second liquid reagent chamber conduit valve 223/446/448/623;
    h) reducing a pressure in the measurement chamber relative to the second liquid reagent chamber;
    i) closing the second liquid reagent chamber conduit valve 223/446/448/623;
    j) performing a measurement in the measurement chamber.

    [0132] FIG. 9 illustrates a flow diagram for a method of operating any of the liquid handling devices 100/200/300/400/500/600 described above and comprising at least a sample chamber 102/202/302/402/502/602, a measurement chamber 104/204/304/404/504/604, a first liquid reagent chamber 106/206/306/406/506/606 and a second liquid reagent chamber 203/408/603. The method is for transferring a sample liquid from the sample chamber to the measurement chamber, then moving a first liquid reagent from the first liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample liquid, then moving a second liquid reagent from the second liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample liquid (optionally wherein the flow direction of the second liquid reagent is also alternate to the flow direction of the first liquid reagent), then moving a further amount of a first liquid reagent from the first liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample liquid and performing a measurement.

    [0133] When a sample has been inserted into the sample chamber 102/202/302/402/502/602, the first liquid reagent chamber 106/206/306/406/506/606 contains a first liquid reagent and the second liquid reagent chamber 203/408/603 contains a second liquid reagent, the method achieves the following:

    a) opening the sample chamber conduit valve 122/222/322/422/522/622;
    b) reducing a pressure in the measurement chamber 104/204/304/404/504/604 relative to the sample chamber 102/202/302/402/502/602;
    c) closing the sample chamber conduit valve 122/222/322/422/522/622;
    d) opening the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    e) reducing a pressure in the measurement chamber relative to the first liquid reagent chamber;
    f) closing the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    g) opening the second liquid reagent chamber conduit valve 223/446/448/623;
    h) reducing a pressure in the measurement chamber relative to the second liquid reagent chamber;
    i) closing the second liquid reagent chamber conduit valve 223/446/448/623;
    j) opening the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    k) reducing a pressure in the measurement chamber relative to the first liquid reagent chamber;
    l) closing the first liquid reagent chamber conduit valve 126/226/326/426/526/626;
    m) performing a measurement in the measurement chamber.

    [0134] The above-described methods can be performed in combination with each other, and in many different orders or multiple times, as required for a given diagnostic test. One method need not be completed before another method is performed.

    [0135] The described methods may be implemented by a diagnostic system using computer executable instructions. A computer program product or computer readable medium may comprise or store the computer executable instructions. The computer program product or computer readable medium may comprise a hard disk drive, a flash memory, a read-only memory (ROM), a CD, a DVD, a cache, a random-access memory (RAM) and/or any other storage media in which information is stored for any duration (e.g. for extended time periods, permanently, brief instances, for temporarily buffering, and/or for caching of the information). A computer program may comprise the computer executable instructions. The computer readable medium may be a tangible or non-transitory computer readable medium. The term “computer readable” encompasses “machine readable”.

    [0136] Thus, also disclosed is a computer program comprising computer-executable instructions which, when executed by a diagnostic system, cause the diagnostic system to perform any of the methods described above.

    Biological Samples

    [0137] In the present invention, the sample liquid may be any suitable biological sample comprising diagnostic biomarkers of interest. In some embodiments, the sample liquid may be a whole blood sample, a serum sample, a saliva sample, a biopsy sample (such as a healthy tissue sample or a tumour sample), a urine sample, a semen sample, a tear sample, a sputum sample, a sweat sample, a mucous sample, a fecal sample, a gastric fluid sample, an abdominal fluid sample, an amniotic fluid sample, a cyst fluid sample, a peritoneal fluid sample, a spinal fluid sample or a synovial fluid sample, although whole blood samples are particularly useful. In a preferred embodiment of the invention the sample liquid is a whole blood sample. The method may include a step of obtaining or providing the biological sample, or alternatively the sample may have already been obtained from a subject, for example in ex vivo methods.

    [0138] Biological samples obtained from a subject can be stored until needed. Suitable storage methods include freezing immediately, within 2 hours or up to two weeks after sample collection. Maintenance at −80° C. can be used for long-term storage. Preservative may be added, or the sample collected in a tube containing preservative. Preferably the sample is analysed immediately following collection.

    [0139] Methods of the invention may comprise steps carried out on biological samples. The sample liquid is considered to be representative of the biomarker status of the biomarkers of interest in difference disease states. Hence the methods of the present invention may use quantitative data on biomarkers of interest, to determine the presence, absence or severity of different disease states.

    [0140] The sample may be processed prior to determining the status of the biomarkers. The sample may be subject to enrichment (for example to increase the concentration of the biomarkers being quantified), centrifugation or dilution. In other embodiments, the samples do not undergo any pre-processing and are used unprocessed (such as whole blood).

    [0141] In some embodiments of the invention, the biological sample may be fractionated or enriched for particular biomarkers prior to detection and quantification (i.e. measurement). The step of fractionation or enrichment can be any suitable pre-processing method step to increase the concentration of a biomarker of interest in the sample. For example, the steps of fractionation and/or enrichment may comprise centrifugation and/or filtration to remove cells or unwanted analytes from the sample, or to increase the concentration of biomarkers of interest in a particular blood fraction. Such methods may be used to enrich the sample for any biomarkers of interest.

    [0142] The methods of the invention may be carried out on one test sample from a subject. Alternatively, a plurality of test samples may be taken from a subject, for example at least 2, at least 3, at least 4 or at least 5 samples from a subject. Each sample may be subjected to a single assay to quantify one of the biomarker panel members, or alternatively a sample may be tested for all of the biomarkers being quantified. Each sample may be subjected to a separate analysis using a method of the invention, or alternatively multiple samples from a single subject undergoing diagnosis could be included in the method.

    [0143] A “sample(s)”, “one or more samples”, sample liquid, or “sample(s) of interest” are terms used interchangeably in singular or plural form and are not intended to be limited to any particular quantity and, as used herein, may be any molecule or substance that the user wishes to gather information from. A sample may become larger or smaller (e.g., by way of inflation or partitioning, respectively) in size, volume or content during the performance of an assay. Accordingly, a sample may be amplified and/or subdivided one or more times during the performance of an assay. In some embodiments, the sample comprises biomarkers of interest.

    [0144] A “liquid”, as used herein, is any aqueous or lipophilic phase capable of flowing freely.

    [0145] The liquid may further comprise one or more reagents, reaction components or samples of interest selected from cells (including any eukaryotic or prokaryotic cells, including but not limited to cells selected from humans, animals, plants, fungi, bacteria, viruses, protozoa, yeasts, molds, algae, rickettsia, and prions); proteins, peptides, antibodies, nucleic acid sequences, oligonucleotide probes, polymerase enzymes, buffers, dNTPs, organic and inorganic chemicals, and fluorescent dyes.

    [0146] The embodiments are not limited to a microfluidic scale but applications on other, for example macroscopic scales, are equally envisaged. For the avoidance of doubt, the term “microfluidic” is referred to herein to mean devices having a fluidic element such as a reservoir or a channel with at least one dimension below 1 mm.

    EXAMPLE 1

    [0147] D-dimer is a small protein fragment that results from fibrin degradation. A D-dimer test is a blood test that can be used to exclude the presence of a serious blood clot. The performance of a D-dimer assay on an electrochemical biosensor was evaluated using two different liquid flow configurations in the same liquid flow system to deliver reagents to the flow cell of an electrochemical biosensor. Each configuration was compared to a control setup using manual filling of the flow cell with a micropipette. For the conventional unidirectional liquid flow only one flow direction (B to A) was used. All assay solutions were loaded sequentially from the B side of the flow cell. These include test sample, enzyme labelled secondary antibody, wash buffer and detection reagents. For the bidirectional liquid flow the test sample and the enzyme labelled secondary antibody were added from the B side of the flow cell (B to A), while the wash buffer and the detection reagent were added from the A side of the flow cell (A to B—FIG. 10).

    [0148] As shown in FIG. 11A the signal obtained for a D-Dimer concentration of 1500 ng/mL for the assay using the bi-directional flow configuration is higher than for the control assay. Conversely, and as shown in FIG. 11B, the signal obtained for the same D-Dimer concentration using the unidirectional flow configuration is significantly lower than for the control assay. The performance of the assay when using bidirectional flow is improved significantly compared to when using unidirectional flow, as measured by signal to control ratio (FIG. 12). FIG. 13 shows the comparison between calibration curves obtained using the bidirectional flow configuration and the control method. Test samples were prepared using fetal bovine serum (FBS) as a matrix for spiking D-Dimer at concentrations ranging from 0-3000 ng/mL. Biosensors were functionalised with capture antibody solution during a one-hour incubation.

    [0149] The following assay workflow was used:

    1. Wash with buffer
    2. Incubate for 5 minutes with test sample pre-mixed with enzyme labelled detection antibody
    3. Wash with buffer
    4. Incubate for 2 minutes with detection reagent
    5. Wash with buffer
    6. Perform differential pulse voltammetry (DPV) measurement

    [0150] The poor signal to noise ratio of the unidirectional flow configuration did not allow the generation of data for a calibration curve. The equivalence of the results obtained with the bidirectional flow configuration and the control method demonstrate the clear advantage of the bidirectional flow configuration over unidirectional flow.

    [0151] The embodiments of the invention shown in the drawings and described above are exemplary embodiments only and are not intended to limit the scope of the appended claims, including any equivalents as included within the scope of the claims. Various modifications are possible and will be readily apparent to the skilled person in the art. It is intended that any combination of non-mutually exclusive features described herein are within the scope of the present invention. That is, features of the described embodiments can be combined with any appropriate aspect described above and optional features of any one aspect can be combined with any other appropriate aspect.

    [0152] Further embodiments of the present invention are described below:

    [0153] 1. A liquid handling device comprising: [0154] a sample chamber for receiving a sample; [0155] a measurement chamber for performing one or more measurements on the sample wherein the measurement chamber comprises a reaction zone; [0156] a first liquid reagent chamber; [0157] a sample chamber conduit which fluidically connects the sample chamber to the measurement chamber; [0158] a sample chamber conduit valve for opening and closing the sample chamber conduit; [0159] a first liquid reagent chamber conduit which fluidically connects the first liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample chamber conduit; and [0160] a first liquid reagent chamber conduit valve for opening and closing the first liquid reagent chamber conduit.

    [0161] 2. The liquid handling device of embodiment 1 wherein the flow direction of the first liquid reagent chamber conduit is at least ninety degrees to the flow direction of the sample chamber conduit, preferably wherein the flow direction of the first liquid reagent chamber conduit is opposite to the flow direction of the sample chamber conduit.

    [0162] 3. The liquid handling device of any previous embodiment, wherein the device further comprises: [0163] a second liquid reagent chamber; [0164] a second liquid reagent chamber conduit which fluidically connects the second liquid reagent chamber to the measurement chamber in an alternate flow direction to the sample chamber conduit; and [0165] a second liquid reagent chamber conduit valve for opening and closing the second liquid reagent chamber conduit.

    [0166] 4. The liquid handling device of embodiment 3 wherein the second liquid reagent chamber conduit fluidically connects to the measurement chamber in an alternate direction to both the sample chamber conduit and the first liquid reagent chamber conduit.

    [0167] 5. The liquid handling device of embodiment 3 wherein the second liquid reagent chamber conduit is fluidically connected to the first liquid reagent chamber conduit thereby providing a combined conduit, fluidically connecting both the first liquid reagent chamber and second liquid reagent chamber to the measurement chamber.

    [0168] 6. The liquid handling device of embodiment 5 wherein the flow direction of the combined conduit into the measurement chamber is at least ninety degrees to the flow direction of the sample chamber conduit into the measurement chamber.

    [0169] 7. The liquid handling device of embodiment 5 or 6 wherein the flow direction of the combined conduit into the measurement chamber is opposite to the flow direction of the sample chamber conduit into the measurement chamber.

    [0170] 8. The liquid handling device of embodiment 4 wherein the flow direction of the second liquid reagent chamber conduit into the measurement chamber is at least ninety degrees to the flow direction of the sample chamber conduit and/or the first liquid chamber conduit into the measurement chamber.

    [0171] 9. The liquid handling device of embodiment 8 wherein the flow direction of the second liquid reagent chamber conduit into the measurement chamber is opposite to the flow direction of the sample chamber conduit and/or the first liquid chamber conduit into the measurement chamber.

    [0172] 10. The liquid handling device of any previous embodiment wherein the reaction zone comprises one or more electrodes.

    [0173] 11. The liquid handling device of embodiment 10 wherein the one or more electrodes comprise one or more electrodes selected from the list: counter electrode, reference electrode and working electrode.

    [0174] 12. The liquid handling device of embodiment 10 or 11 wherein the one or more electrodes comprise at least one working electrode.

    [0175] 13. The liquid handling device of any previous embodiment wherein the device comprises two or more measurement chambers, each of which is fluidically connected to the sample chamber and each of which is fluidically connected to the first liquid reagent chamber, [0176] wherein the device comprises a corresponding number of sample chamber conduit valves and/or first liquid reagent chamber valves for independent control of the flow of sample liquid and/or first liquid reagent into each measurement chamber.

    [0177] 14. The liquid handling device of embodiment 13, wherein the device further comprises a second liquid reagent chamber and wherein each of the measurement chambers is fluidically connected to the second liquid reagent chamber, and [0178] wherein the device comprises a corresponding number of second liquid reagent chamber conduit valves for independent control of the flow of second liquid reagent into each measurement chamber.

    [0179] 15. The liquid handling device of embodiment 14, wherein the second liquid reagent chamber conduit is fluidically connected to the first liquid reagent chamber conduit thereby providing one or more combined conduits fluidically connecting both the first liquid reagent chamber and second liquid reagent chamber to each measurement chamber.

    [0180] 16. The liquid handling device of any previous embodiment, wherein the flow of any one or more of the sample liquid, first liquid reagent and/or the second liquid reagent into each of the measurement chambers can be independently controlled to regulate the residence time of each liquid in each of the measurement chambers.

    [0181] 17. The liquid handling device of embodiment 16 wherein the flow of any one or more of the sample liquid, first liquid reagent and/or the second liquid reagent is controlled such that the residence time of each liquid is a predetermined period of time.

    [0182] 18. The liquid handling device of any previous embodiment, wherein the device further comprises: [0183] a mixing zone located between the sample chamber and the measurement chamber and wherein the mixing zone is fluidically connected to both the sample chamber and the measurement chamber.

    [0184] 19. The liquid handling device of embodiment 18, wherein the mixing zone comprises a mixing chamber, wherein the mixing chamber is fluidically connected to the sample chamber conduit and to the measurement chamber by a mixing chamber conduit.

    [0185] 20. The liquid handling device of any one of embodiments 18 or 19 wherein the device further comprises: [0186] a third liquid reagent chamber; [0187] a third liquid reagent chamber conduit which fluidically connects the third liquid reagent chamber to the mixing zone, optionally wherein the third liquid reagent chamber conduit connects to the mixing zone in an alternate flow direction to the sample chamber conduit; and [0188] a third liquid reagent chamber conduit valve for opening and closing the third liquid reagent chamber conduit.

    [0189] 21. A method of performing a diagnostic assay comprising sequentially moving liquid from a sample chamber to a measurement chamber and moving a first liquid reagent into the measurement chamber from an alternate flow direction, the method including: [0190] filling the sample chamber with sample liquid; [0191] moving sample liquid from the sample chamber to the measurement chamber; [0192] retaining the sample liquid in the measurement chamber for a predetermined period of time, [0193] moving a first liquid reagent from a first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample chamber liquid and taking a measurement, optionally wherein the first liquid reagent is retained in the measurement chamber for a predetermined period of time.

    [0194] 22. The method of embodiment 21 wherein the first liquid reagent is removed from the measurement chamber before the measurement is taken.

    [0195] 23. The method of embodiment 21 or embodiment 22, further comprising a step of moving liquid from a second liquid reagent chamber to the measurement chamber in an alternate flow direction to sample liquid.

    [0196] 24. A method of performing a diagnostic assay comprising sequentially moving liquid from a sample chamber to a measurement chamber and moving a first and second liquid reagent into the measurement chamber from an alternate flow direction, the method including: [0197] filling the sample chamber with sample liquid; [0198] moving sample liquid from the sample chamber to the measurement chamber; [0199] retaining the sample liquid in the measurement chamber for a predetermined period of time, [0200] moving a first liquid reagent from a first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid; [0201] moving a second liquid reagent from a second liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid and performing a measurement, optionally wherein the first and second liquid reagents are each retained in the measurement chamber for a predetermined period of time.

    [0202] 25. The method of embodiment 24 wherein the second liquid reagent is removed from the measurement chamber before the measurement is taken.

    [0203] 26. A method of performing a diagnostic assay comprising sequentially moving liquid from a sample chamber to a measurement chamber and moving a first and second liquid reagent into the measurement chamber from an alternate flow direction, the method including: [0204] filling the sample chamber with sample liquid; [0205] moving sample liquid from the sample chamber to the measurement chamber; [0206] retaining the sample liquid in the measurement chamber for a predetermined period of time, [0207] moving a first liquid reagent from a first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid; [0208] moving a second liquid reagent from a second liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid; [0209] moving a further volume of the first liquid reagent from the first liquid reagent chamber into the measurement chamber in an alternate flow direction to the sample liquid and performing a measurement, optionally wherein the first and second liquid reagents are each retained in the measurement chamber for a predetermined period of time.

    [0210] 27. The method of any one of embodiments 21-26 wherein the flow direction of the first liquid reagent and/or the second liquid reagent is at least ninety degrees to the flow direction of the sample liquid into the measurement chamber, preferably wherein the flow direction of the first liquid reagent and/or second liquid reagent is opposite to the flow direction of the sample liquid.

    [0211] 28. The method of any one of embodiments 21-27, further comprising a step of mixing the sample liquid with one or more additional reagents before moving the sample liquid into the measurement chamber.

    [0212] 29. The method of embodiment 28 wherein the sample liquid is mixed in a mixing zone with a third liquid reagent from a third liquid reagent chamber.

    [0213] 30. A method of implementing the method described in any one of embodiments 21-29 on a device of any one of embodiments 1-20.

    [0214] 31. The liquid handling device of any one of embodiments 1-20 or the method of any one of embodiments 21-30 wherein the first liquid reagent is any liquid composition suitable for use as a washing liquid in immunoassays, for example a wash buffer.

    [0215] 32. The liquid handling device or the method of embodiment 31 wherein the first liquid reagent is a liquid comprising one or more reagents selected from the list of a pH buffer (e.g. PBS, Tris, carbonate/bicarbonate, HEPES, MOPS, MES), a salt solution (e.g. NaCl, KCl, MgCl.sub.2), a detergent (e.g. Tween 20, Tween 80, Triton-X, CHAPS) and a stabilizer/blocking agent (e.g. BSA, casein).

    [0216] 33. The liquid handling device or the method of embodiment 32 wherein the first liquid reagent is Tris-buffered saline (TBS) and phosphate-buffered saline (PBS) containing 0.05% (v/v) Tween®-20.

    [0217] 34. The liquid handling device of any one of embodiments 1-20 and 31-33 or the method of any one of embodiments 21-33 wherein the second liquid reagent is a detection reagent for use in immunoassays.

    [0218] 35. The liquid handling device or method of embodiment 34 wherein the second liquid reagent comprises one or more reagents selected from DAB (3, 3′-diaminobenzidine), metal-enhanced DAB, AEC (3-amino-9-ethylcarbazole), BCIP (5-bromo-4-chloro-3-indolyl phosphate), NBT (nitro-blue tetrazolium chloride), TMB (3,3′,5,5′-tetramethylbenzidine), ELF (enzyme-labelled fluorescence) and OPD (ophenylenediamine dihydrochloride), preferably wherein the second liquid reagent comprises 3,3′,5,5′-Tetramethylbenzidine (TMB).

    [0219] 36. The liquid handling device of any one of embodiments 1-20 and 31-35 or the method of any one of embodiments 21-35 wherein the predetermined period of time is from 1 to 180 seconds (e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179 or 180 seconds).

    [0220] 37. The liquid handling device of any one of embodiments 1-20 and 31-36 or the method of any one of embodiments 21-36 wherein the predetermined period of time is from 1 to 60 seconds (e.g. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60 seconds).

    [0221] 38. The liquid handling device of any one of embodiments 1-20 and 31-37 or the method of any one of embodiments 21-37 wherein the predetermined period of time is from 10 to 30 seconds (e.g. 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 seconds).

    [0222] 39. The liquid handling device of any one of embodiments 1-20 and 31-36 or the method of any one of embodiments 21-36 wherein the predetermined period of time is from 60 to 180 seconds (e.g. 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179 or 180 seconds).

    [0223] 40. A computer program comprising computer-executable instructions which, when executed by a system, cause the system to perform the method according to any of embodiments 21 to 39.

    [0224] 41. A system comprising a processor configured to execute the computer program according to embodiment 40.