Soft robotics allow for safe interactions with humans, which is imperative for healthcare applications and wearable electronic devices. Smart materials—including shape-memory polymers, pneumatic polymers, hydrogels, and electroactive polymers—have all demonstrated utility in various applications, but each mode of actuation possesses drawbacks.
Electromagnetic actuators (EMAs) are controlled by a magnetic field, leading to high-performance systems with small sizes, fast response times, and high power efficiency. However, these devices typically use rigid components, which are not amenable to soft robotics.
Professor Yon Visell of the California NanoSystems Institute, UC Santa Barbara, and co-workers have developed a method to fabricate soft electromagnetic actuators (SEMAs) that is both inexpensive and scalable. The SEMAs are thermally efficient, polymodal, and can operate at high frequencies and low voltages.
3D helical inductors composed of silicone polymer colloids, eutectic gallium indium alloy, and magnetic powder (NdFeB) were mechanically coupled to permanent magnets and flexible elastic membranes to form actuators. Soft vibrotactile actuators (SVAs) that can deliver mechanical stimuli to the skin were fabricated from these soft helical coils, as well as a soft electromagnetic gripper (SEMG). The SEMG is able to pick up miniature payloads, including a small piece of foam (2.89 mg), a PDMS cube (3.61 mg), and a preserved carpenter ant (13 mg).