Tendril‐Inspired Programmable Liquid Metal Photothermal Actuators for Soft Robots

Abstract

Photothermal actuators are widely applied in robots, smart devices, and bionic systems. However, asymmetric thermal expansion, the most common mechanism for preparing photothermal actuators, has not been utilized in programmable liquid metal photothermal actuators. In this work, Liquid metal/Polyimide/Polytetrafluoroethylene (LM/PI/PTFE) programmable photothermal actuators based on asymmetric thermal expansion are prepared inspired by the climbing plant tendrils. The “protoplasm that can contract and bend” PTFE tape endows the photothermal actuator with programmable initial morphology. The photothermal properties and flexibility of the liquid metal microspheres, together with the significant property difference between PI and PTFE, endow the photothermal actuator with excellent response angles (130.74 ± 6.45°), response speeds (46.62 ± 2.33° s−1), stability (2000 cycles for 10 h), and load‐carrying capacity, which are not inferior to most of the reported PI photothermal actuators. The LM/PI/PTFE photothermal actuator has been successfully modelled and simulated by finite element analysis (FEA). Based on the programmable initial morphology and the simulation by FEA, this work has designed and prepared a variety of bionic systems and functional robots. The work of LM/PI/PTFE photothermal actuators provides a strategy for designing photothermal actuators and enables the future development of photothermal actuators in bionic systems and robots.

Design and mechanism of photothermal soft actuators and their applications

“…Li et al developed liquid metal/polyimide/polytetrafluoroethylene (LM/PI/PTFE) programmable photothermal actuators inspired by climbing plant tendrils. 215 The grasping robot, as depicted in Fig. 12a, was designed to mimic an eagle's claw.…”