Ring-shape SMA micro actuator with parylene retention spring for low power consumption, large displacement linear actuation

Abstract

This paper reports a novel ring-shape micro actuator for a latching mechanism used in a low power consumption and large displacement micro linear actuation. The proposed actuator consists of a shape memory alloy (SMA) ring, parylene spring and shoes. The parylene spring was carefully designed for independent control of radial and axial stiffness, which can be realized by a high aspect ratio cross section and a meander structure. The maximum force generated by the parylene spring was about 40 mN. Two types of SMA actuator was examined for the actuation: simple wire and micro spring types. The maximum displacement as high as 300 μm was obtained by using the SMA micro spring.