Heating and actuation characteristics of shape memory thin film actuator for blood vessel holding

In this paper, we describe a pulsation sensor with an actuator of shape memory alloy (SMA) thin film (20 mum thick) to hold a small blood vessel at an anastomosis site. Heating and actuation characteristics of the SMA thin film actuator with thin film thermocouples were studied in gelatin as a simulative tissue of human body. Although, in air, the temperature of the actuator rose up to the deformation temperature (65degC) of the SMA film within 1 s when the actuator was heated in air at 3.8 mA (0.044 W), in gelatin, longer time heating with a larger current was necessary to achieve the deformation temperature due to the heat loss to the surrounding gelatin. However, under this constraint condition with surrounding gelatin, the SMA actuator was successfully released from a silicon tube embedded in the gelatin layer.