Wednesday  |  Conference Center B  |  09:00 AM–09:20 AM

#13476, Snap-through Instability Enables Fast Soft Robots Based on Thermal Actuation

Soft robots are constructed from highly compliant materials. In contrast to their rigid counterparts, they allow adaptability to changing environments and dynamic task settings. Yet no actuation method has emerged as the dominant method for soft robotics. Electrothermal actuation shows several appealing features such as programmable operation, lightweight, low actuation voltage, and potential for untethered operation (e.g., via wireless charging). Thermal actuation is a common actuation method for soft robots. However, a major limitation is the relatively slow actuation speed. Here we report significant increase in the actuation speed of a bimorph thermal actuator by harnessing the snap-through instability. The actuator is made of silver nanowire/polydimethylsiloxane composite. The snap-through instability is enabled by simply applying an offset displacement to part of the actuator structure. The effects of thermal conductivity of the composite, offset displacement, and actuation frequency on the actuator speed are investigated using both experiments and finite element analysis. The actuator yields a bending speed as high as 28.7 cm-1/s, 10 times that without the snap-through instability. A fast-crawling robot with locomotion speed of 1.04 body length per second and a biomimetic Venus flytrap were demonstrated to illustrate the promising potential of the fast bimorph thermal actuators for soft robotic applications.

Submission to Symposium on "Recent Advances in Imaging Methods, Machine Learning, and Applications"

Shuang Wu   North Carolina State University
Yong Zhu   North Carolina State University