Soft and Wet Conducting Polymers for Artificial Muscles

Muscles convert chemical energy to mechanical energy plus heat at constant temperature. The search for artificial muscles that do the same is described, beginning with polymer gels—which were restricted to slow movements and had high energy consumption—and ending with the bilayer devices that have been constructed from conducting polymers more recently. The mechanism of operation of these devices is explained, showing how the electrochemically stimulated conformational movements of the conducting polymer chains are translated into macroscopic movements.