Thrombus sensor with a microvascular holding actuator

In this paper, we describe a thrombus sensor, which is integrated with a TiNiCu ternary shape memory alloy (SMA) thin film actuator arm for microvascular holding. The actuator arm of the sensor has micro-heaters to heat up the SMA film locally for actuations of holding and releasing a fine blood vessel. The arm can hold a vessel of 1mm in outer diameter and pulsation was detected mechanically by a displacement sensor of a cantilever, on which strain gauges of Pt thin film lines are formed. Sensitivity of the displacement measurement of the cantilever was about 0.1 mV/μm. In vivo measurement of a femoral artery pulsation waveform of a laboratory rat was examined. The sensor could detect a decrease of amplitude of pulsation waveform caused by a bloodstream obstruction successfully. Normal pulsation waveform was measured with amplitude of about 3.5 mV. However, it decreased to 1 mV when the bloodstream was obstructed.