1, Seoul National University, Seoul, , Korea (the Republic of)
2, Seoul National University, Seoul, , Korea (the Republic of)
Shape memory alloy (SMA) is widely utilized material as an actuation source of soft actuators by embedding it in elastomeric polymers. It is known that the SMA possesses simple actuation mechanism and high power density, but also has limitations in terms of strain range and actuation speed. In this research, we designed, fabricated, and evaluated an SMA based high-speed microscale actuator. Diamond-shaped SMA frame structures with 1–1.5 μm in thickness were fabricated using a focused ion beam (FIB) milling process. The behavior of these structures under mechanical deformation and changes in thermal conditions was investigated to use these as a driving source for a high-speed microscale actuator. The diamond-shapes frame structure allows large elongation range (~40 %) compared to bulk SMA materials (~5 %) with the aid of spring-like behavior under tensile deformation. In addition, shape memory effect (SME) was triggered at these structures by applying thermal energy delivered with ultraviolet (UV) laser. The reaction force and response speed were investigated according to changes in the laser switching speed and the irradiation energy. The fast heating and cooling phenomenon caused by the scale effect allows high-speed actuation of SMA up to 1,500 Hz, which is 40 times faster than the previous result (35 Hz). We expect that the proposed actuators can contribute to the development of micro- and nanoscale soft robots, electronic equipment or medical devices.