Note: A novel curvature-driven shape memory alloy torsional actuator

This paper presents a novel, extremely simple torsional actuator which employs a special shape setting treated shape memory alloy coil. The actuator works with a so-called curvature-driven principle and can directly generate a rotary motion without any motion converting mechanism. Experiments were performed to study the output performances of several actuators with different geometry parameters. The test results show the actuator can output a rotary motion fluently, and the output torque is about several mN mm.