Abstract
In nature, the dynamic contraction and relaxation of muscle in animals provide the essential force and deformation necessary for diverse locomotion, enabling them to navigate and overcome environmental challenges. However, most autonomous robotic systems still rely on conventional rigid motors, lacking the adaptability and resilience of muscle-like actuators. Existing artificial muscles, while promising for soft actuation, often require demanding operational conditions that hinder their use in onboard-powered small autonomous systems. In this work, we present the Elasto-Electromagnetic mechanism, an electromagnetic actuation strategy tailored for soft robotics. By structuring simple elastomeric materials, this mechanism mimics key features of biological muscle contraction and optimizes actuation properties. It achieves significant output force (~210 N/kg), large contraction ratio (up to 60%), rapid response (60 Hz), and low-voltage operation (<4 volts) within a robust, miniaturized framework. It also enhances energy efficiency by maintaining stable states without continuous power input, similar to catch muscles in mollusks. The resulting insect-scale soft robots, therefore, demonstrate adaptive crawling, swimming, and jumping, autonomously navigating open-field environments. This muscle-inspired electromagnetic mechanism, facilitated by elastic structural variations, expands the autonomy and functional capabilities of small-scale soft robots, with potential applications in rescue and critical signal detection.