In order to promote the pulmonary circulation after Fontan procedure, we have been developing a pediatric pulmonary circulatory assist device using shape memory alloy (SMA) fibers. In this study, we developed the sensorless control system for the pulmonary circulatory assist device and examined its fundamental functions. The SMA fiber shows a linear relationship between the internal resistance and longitudinal contraction. We measured a change in current of the fiber during the operation. After driving, the current was 1.8A rises from 1.4A due to contraction of the fiber, and peak value was measured at the complete contraction. We could be achieved monitoring of the contractile condition by the current change. It was indicated the system could be reduce of overheating and decrease in contractile force of the device. In the application of the control method, the high-reliability system as the implantable device might be achieved.
