Fabrication and Characterization of an Arrayed Shape Memory Alloy Thick Film Actuator Device for Planar Tactile Displays

Abstract

This paper describes the fabrication and characterization of a shape memory alloy (SMA) thick film actuator array for MEMS-type tactile displays that present information to a human finger with mechanical stimulation. A planar SMA thick film actuator array (5×5 array, 1 mm pitch) is proposed as a core component of tactile displays. A prototype of the MEMS-type SMA actuator array device with planar meandering SMA actuators and Pt thin film micro-heaters was successfully fabricated from a 10 µm thick SMA flash-evaporated film through a novel fabrication processes. The basic force generation properties of the completed SMA actuator were evaluated by heating the Pt micro-heater. When the device initially deflected to 100 µm, it was able to generate 33 mN and 16 mN of force by heating with 15 mA of DC current and without heating, respectively. In the combination with a bias spring, reversible force generation and displacement were estimated to be 5 mN and 20 µm when driven with a DC current, respectively. The force generated by the SMA actuator during vibrational motion at 20-40 Hz decreased to half the force generated during static motion. However, the output force was expected to be large enough to mechanically stimulate a human finger at 20-40 Hz.