Smart Polymer Brushes Offer Safer Electromechanical Muscle Leaps
Scientists have developed a new material to enable comfortable and safe artificial muscles. The discovery comes from researchers reporting findings to the American Chemical Society and offers a potential path toward practical robotic actuators. The breakthrough centers on polymer brushes that serve as electroactive elastomers, a class of materials designed to move in response to electrical signals while remaining light and compact. These brushes act as linear actuators that can mimic natural muscle motion with fast clamping and decompressing capabilities while staying within safer voltage ranges.
Traditionally human and animal movement relies on contractile muscle fibers to create motion. For decades, engineers have searched for an equally effective linear mover for robots that combines strength, reliability, lightness, and simplicity. The challenge has always been to generate robust motion without complex energy management or bulky power sources. Electroactive elastomer brushes emerge as a promising answer because they can convert electrical energy directly into controlled mechanical work, enabling compact, high-speed actuation with scalable force outputs.
A key hurdle has been the voltage required to drive these materials. Experiments currently use voltages around 4000 volts, a level far above safety standards in many countries. This creates practical barriers to widespread use, even if the materials prove capable of performing. Researchers addressed this issue by focusing on the thickness of the brush films. By reducing the film thickness, the stress on the material decreases and the operating voltage can be lowered without sacrificing the actuation strength. This approach aligns with a broader effort to make smart materials safer and more accessible for real world robotics and assistive devices.
In practice, the team synthesized a series of brushes by joining polydimethylsiloxane macromonomers with norbornene and exposing the mixture to ultraviolet light. The resulting material at a thickness of 60 microns demonstrated enhanced electroactivity, expanding more than earlier elastomer formulations at an operating voltage of about 1000 volts. The practical drive built from this material endured roughly ten thousand cycles before showing signs of failure, a promising indicator of durability and reliability for potential commercial use. These results underscore how careful control of film geometry can unlock substantial performance gains in electroactive systems.
Looking ahead, researchers expect that further optimization may bring operating voltages down even further. The ultimate goal is a safe and practical electromuscular system that can operate near 50 volts, broadening the horizon for affordable, safe, and efficient artificial muscles. Real world applications could span from soft robotics and prosthetic devices to responsive haptic systems and precision actuation in industrial automation. The ongoing work continues to refine material composition, brush architecture, and manufacturing processes to translate laboratory successes into usable technology with meaningful real world impact. [ACS 2024]