Magnetic putty as a reconfigurable, recyclable, and accessible soft robotic material

Abstract

Magnetically hard materials are widely used to build soft magnetic robots, providing large magnetic force/torque and macrodomain programmability. However, their high magnetic coercivity often presents practical challenges when attempting to reconfigure magnetization patterns, requiring a large magnetic field or heating. In this study, magnetic putty is introduced as a magnetically hard and soft material with large remanence and low coercivity. It is shown that the magnetization of magnetic putty can be easily reoriented with maximum magnitude using an external field that is only one-tenth of its coercivity. Additionally, magnetic putty is a malleable, autonomous self-healing material that can be recycled and repurposed. The authors anticipate magnetic putty could provide a versatile and accessible tool for various magnetic robotics applications for fast prototyping and explorations for research and educational purposes. Permanent magnetic particles embedded in a viscoelastic putty matrix result in a self-healing soft magnetic material with both high remanence and low coercivity, providing hard-magnetic performance without the need for inaccessible strong magnetic fields. Programmable and reconfigurable magnetization, frequency-dependent force output, and easy to shape and assemble, magnetic putty can be a versatile tool in research prototyping and inspire future explorations.