Shape‐Memory Alloy Torsion Strips for Soft Robotic Manipulation and Morphing

Mimicking invertebrates, soft robots tend to control each of their body joints to achieve the desired shape changes and movements to accomplish different tasks. Shape‐memory alloy (SMA) is a common actuation material but needs to be designed into specific shapes to disperse local strains. In this article, a dedicated configuration of SMA strips is introduced for soft robotic body joint manipulation and morphing. Inspired by the Möbius strip, the proposed SMA torsion strip (STS) can meet the requirements of both large deformation and large force output desirable for robotic applications. Compared to conventional morphing methods, the STSs can supply considerable torque output over a wide range of bending angles to freely chosen body joints. Therefore, both pattern‐to‐pattern extreme shape morphing, such as tendrils curling, and programmable shape morphing can be achieved. A mathematical model is established to describe how geometry and temperature affect the STS properties to optimize performance. Due to the extensibility of the STS, it can be used for a large variety of robotic applications that are partially illustrated in this research as artificial muscles, grippers, jumping robots, and soft proportional valves.