Untethered Nanotextured Thermopneumatic Soft Actuators Operable with Different Stimuli: Thermal Blowing, Infrared Light, and Electromagnetic Field

Abstract

In this study, untethered nanotextured thermopneumatic soft actuators (UTPSAs) were developed using a soft elastomer body encapsulating a volatile fluid (Novec 7000), which underwent a phase change (evaporation) when stimuli that convert energy into heat were applied using wireless transmission. Herein, we analyzed three types of stimuli: (i) thermal blowing, (ii) irradiation with infrared light, and (iii) electromagnetic energy transmission. In the third case, an electromagnetic field induced an electric current in a wire coil embedded in an elastomeric body, thus providing Joule heating to induce fluid evaporation. The bending curvature and force generated during bending were examined under various operational conditions, which enable one to select the optimal operating mechanism of UTPSAs for a specific environment. Specifically, diverse operating capabilities of UTPSAs are expected to be useful in dynamic environments, e.g., rescue situations. In addition, as a potential application, a crawler-configured UTPSA was fabricated, and its operation was demonstrated.