Platelet Function Analyzer: Shear Activation of Platelets in Microchannels

Platelet function is suggestive of pathological conditions in cardiovascular diseases. With current insufficient prognostic devices, the need exists for a device to assess complete platelet function. This work presents a preliminary microfluidic device for such analysis based on platelet adhesion under shear flow conditions. In this novel device, polydimethylsiloxane (PDMS) microchannels were coated using a layer-by-layer self-assembly technique to provide controlled nanometer-thick layers of fibrinogen. Anticoagulated platelet rich plasma labeled with a fluorescein isothiocynate-tagged anti-glycoprotein IIb/IIIa-antibody and acridine orange was passed through these micro-channels at various time-averaged shear rate values. Fluorescence assays confirmed shear-dependent adhesion of platelets in the microchannels. Control experiments showed that the extent of adhesion on bare PDMS surfaces was less than on the surfaces coated with fibrinogen at similar shear rates. Fluorescent microscopy demonstrated that the extent of platelet adhesion to the fibrinogen substrate depended on shear rate. The extent of adhesion was modeled as a third order polynomial in shear rate.