Pulsation sensor integrated with microvascular holding actuator for thrombosis monitoring

In this paper, we describe a micro-pulsation sensor, which is integrated with a TiNiCu ternary shape memory alloy (SMA) thin film actuator arm for microvascular holding. The actuator arm has micro-heaters to heat up the SMA film locally for actuations of holding and releasing a fine blood vessel. Pulsation was detected successfully by a mechanical deflection of an SMA cantilever, on which strain gauges of Pt thin film lines were formed. Obtained sensitivities of the displacement measurement of the cantilever were about 0.1 mV/μm and 0.08 mV/μm for static and dynamic deflections, respectively. In vivo measurement of a femoral artery pulsation of a laboratory rat was conducted. The sensor could detect a normal pulsation waveform with amplitude of about 3.5 mV. The sensor could also successfully detect a decrease of amplitude of pulsation waveform caused by a bloodstream obstruction.