Blood Analysis

Blood coagulation tests are an integral part of diagnosis and treatment of patients with cardiac disorders. The activated partial thromboplastin time test (aPTT or APTT) is performed on a large scale, in laboratories, to monitor the functioning of the intrinsic and common pathways of the blood coagulation cascade and the concentration of anticoagulants such as heparin among patients. A polydimethylsiloxane (PDMS) based microfluidic device has been fabricated and tested to perform APTT as a point-of-care device using whole blood samples by detecting the change in electrical impedance of blood during coagulation. A portable setup consisting of the device and a lock-in amplifier circuit was built and tested for repeatability and stand alone usage. A frequency sweep test was performed on the device and the optimal frequency of operation for maximum output sensitivity was determined. The devices were also tested for their sensitivity to different concentrations of heparin and found to exhibit an expected increase in coagulation time for increasing heparin concentration.

References:

• Microfluidic device and system for point-of-care blood coagulation measurement based on electrical impedance sensing, B. Ramaswamy, Y. T. Yeh, and S. Y. Zheng, Sensors and Actuators B: Chemical, vol. 14(1), pp. 235-245, 2012. [Link]