Microfluidic chip-based, universal coagulation assay
A microfluidic, chip-based assay device has been developed for measuring physical properties of an analyte (particularly, whole blood or whole blood derivatives). The technologies can be applied to measure clotting times of whole blood or blood derivatives, determine the effects of anticoagulant drugs on the kinetics of clotting/coagulation, as well as evaluate the effect of anticoagulant reversal agents. These technologies can additionally be used to optimize the dosage of anticoagulation drugs and/or their reversal agents. The assay is independent of the presence of anticoagulant; clotting is activated by exposure of the blood sample in the device to a glass (or other negatively charged material such as oxidized silicon) surface, which activates the intrinsic pathway and can be further hastened by the application of shear flow across the activating materials surface. The absence of chemical activating agents and highly controlled and reproducible micro-environment yields a point of care universal clotting assay.
1. A test microchip for measuring clotting in a blood or plasma sample, the test microchip comprising:
an inlet for the blood or plasma sample, the inlet communicating with one or more microchannels having a length between tens of microns and millimeters, each microchannel comprising one or more test chambers, each microchannel having a defined volume between nanoliters and milliliters and configured to draw the blood or plasma sample into the one or more test chambers by passive capillary action,
the one or more microchannels communicating with an outlet and each of the one or more microchannels comprising at least one anionically charged surface which activates clotting of the blood or plasma sample upon entry of the blood or plasma sample into the one or more microchannels or test chamber, wherein the anionically charged surface does not include chemical agents activating clotting, and
wherein changes in optical properties indicative of clot formation can be measured.
2. The test microchip of claim 1 , wherein the test chamber is formed of material which allows changes in the optical properties in the blood or plasma to be measured by infrared transmission.
3. The test microchip of claim 2 , wherein the test microchip comprises a single microchannel.
4. The test microchip of claim 2 , wherein the test microchip comprises electrodes or patterned metal sheets or films.
5. A microassay device for measuring clotting in a blood or plasma sample from an individual, the device comprising a test microchip, the test microchip comprising:
an inlet for the blood or plasma sample, the inlet communicating with one or more microchannels having a length between tens of microns and millimeters, each microchannel comprising one or more test chambers, each microchannel having a defined volume between nanoliters and milliliters and configured to draw the blood or plasma sample into the one or more test chambers by passive capillary action,
the one or more microchannels communicating with an outlet and each of the one or more microchannels comprising at least one anionically charged surface which activates clotting of the blood or plasma sample upon entry of the blood or plasma sample into the one or more microchannels or test chamber, wherein the anionically charged surface does not include chemical agents activating clotting, and
wherein changes in optical properties indicative of clot formation can be measured,
wherein the test microchip is inserted into a reader, the reader comprising
a detector which determines changes in optical properties in the blood or plasma sample to measure clotting time, and
a temperature control regulating the temperature of the test chamber,
wherein the detector is configured to output the measured clotting time from the time of activation of the sample to the time of change in the optical properties in the test chamber indicative of clotting.
6. The microassay device of claim 5 , wherein the output of the reader is provided on a display.
7. The microassay device of claim 5 , wherein the reader comprises an integrated heater for controlling the temperature of the test chamber in the inserted test microchip.
8. The microassay device of claim 5 , wherein the detector comprises an infrared source and an infrared detector, positioned to detect a change in absorbance in the sample in the test chamber of the inserted test microchip.
9. A method for measuring clotting time comprising the steps of
applying a blood or plasma sample to the test microchip of claim 1 in a reader for measuring clotting in the blood or plasma sample,
wherein the reader comprises
a detector which determines changes in optical properties in the blood or plasma sample to measure clotting time, and
a temperature control regulating the temperature of the test chamber,
wherein the detector is configured to output the measured clotting time from the time of activation of the sample to the time of change in the optical properties in the test chamber indicative of clotting; and
obtaining outputting of the clotting time.
10. The method of claim 9 , wherein the optical properties in the blood or plasma in the test chamber are measured by IR transmission.