Nanostructured Shape Memory Alloy based Artificial Muscle for Bio-inspired Robotics

Abstract

Artificial muscles have been used in various applications, from small to large scale robots, especially bio-inspired robots. Among many types of artificial muscles, shape memory alloy (SMA), which can be actuated through heating and cooling, have the advantage of generating high force with large deformation, thus many studies have been conducted on their application as artificial muscles. However, limited actuation speed and bandwidth of shape memory alloy was troublesome for long time due to remarkably slow cooling rate compared to the heating. While some applications used active cooling components such as heavy and bulky air or liquid pumps, they depreciated the merit of SMA being lightweight and shape-conformable. Therefore, in this work, we focused on increasing cooling rate under natural cooling by maximizing thermal dissipation of SMA. Specifically, Cu nanowire with high thermal conductivity was directly grown on the surface of SMA which resulted with increasing the surface area of the SMA for facile heat dissipation. Accelerated cooling of Cu nanowire grown SMA showed faster actuation compared to the bare SMA, and it was successfully applied to biomimetic with enhanced working speed.