Deforming materials with light: Photoresponsive materials muscle in on the action
Pound for pound muscle packs a real punch with a performance that exceeds engines and motors of a similar size. Given this observation, it’s perhaps no surprise that making an artificial muscle of equivalent output to natural muscle is a huge challenge that has so far eluded researchers. An artificial muscle generating around 100 W/kg with a response time of less than a second and an energy conversion efficiency of 30% or so would be very nice. Add in silent operation, 10 million or more operating cycles, self-repair and self-sensing and then we would be getting closer to muscle. Finally, we would want to be able to fabricate these systems from microscopic MEMS devices to macroscopic actuators for humanoid robots (and a vast array of applications in between). In some respects, different types of artificial muscles can mimic most of these muscle functions, albeit with less sophisticated structures. However, the combination of all these functions into a single material remains the greatest challenge. Muscle provides both a guide and inspiration to keep pushing the boundaries in artificial muscle technologies.