An oscillated, self-sensing piezoresistive microcantilever sensor with fast fourier transform analysis for point-of-care blood coagulation monitoring

We present a real-time blood coagulation monitoring by using an externally vibrated, self-sensing piezoresistive microcantilever sensor for disposable point-of-care coagulation device. As the piezoresistive microcantilever was immersed in the sample solution, the measurement was performed in a vibration at fixed frequency and fixed amplitude. During the blood coagulation reaction, the viscosity of the sample suddenly rises due to the clot formation. The increased force can be sensed when the resistance amplitude rises. The acquired signal of resistance change that resists to the motion of the beam was processed by Fast Fourier Transform (FFT) algorithm to filter disturbed signals, and the resistance amplitude indicated the measured force exerting onto the cantilever. With such a self-sensing cantilever sensor technique and FFT analysis system, the prothrombin time (PT) result measured by the self-sensing microcantilever technique exhibits a strong correlation with that of clinically used prothrombin time measured by the commercial instrument of mechanical detection. Moreover, this work quantitatively characterizes the entire viscosity changes of a biochemically induced time-dependent reaction in blood coagulation, while the conventional Sonoclot measurement technique simply provides qualitative information.