Bio-Inspired Polymer Composite Actuator and Generator Driven by Water Gradients

Mini Mighty Muscle Actuators—or artificial muscles—take electrical or chemical energy and convert it into mechanical force. Typically, actuators made from polymers can show large deformations, but cannot generate a lot of force. Ma et al. (p. 186 ; see the Perspective by Kim and Kwon ) describe a polymer composite based on a modified polypyrrole that expands in response to water absorption. The composite was able to generate large stresses and forces, and offered a high work density approaching those of the best conducting polymer electrochemical actuators. Magnetic nanoparticles incorporated into polymer films were used to control the locomotion of the actuator.