Microfluidic chip-based, universal coagulation assay

A microassay system for measuring clotting in a blood or plasma sample from an individual, the system comprising a test microchip and a reader, the test microchip comprising:

• an inlet for a blood or plasma sample, the inlet communicating with a single microchannel having a length between tens of microns and millimeters,
• the microchannel comprising one or more test chambers, the 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 microchannel communicating with an outlet and the microchannel comprising at least one anionically charged surface configured to activate clotting of the blood or plasma sample upon entry of the blood or plasma sample into the microchannel,
• wherein the at least one anionically charged surface comprises a first surface of glass and a second surface of oxidized silicon,
• wherein the at least one anionically charged surface does not include chemical agents activating clotting,
• wherein changes in optical properties of the blood or plasma sample indicative of clot formation can be measured in the one or more test chambers,
• wherein the test microchip is inserted into the reader, the reader comprising:
• a detector configured to determine changes in optical properties in the blood or plasma sample to measure clotting time, 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 and
• a temperature control configured to regulate the temperature of the one or more test chambers,
• wherein the detector is configured to output the measured clotting time from the time of activation of the sample to a time of change in the optical properties in the one or more test chambers indicative of clotting.