Conducting Polymer Electromechanical Actuators

Abstract

Conducting polymer charge-transfer complexes are evaluated as electromechanical materials for the direct conversion of electrical energy to mechanical energy. Large dimensional changes upon electrochemical doping/dedoping provide the mechanical response for proposed extensional, pneumatic, bimorph, and micromechanical actuators. Actuator performance is predicted using both the observed performance of electrochromic devices, electrochemical transistors, and batteries and observed polymer properties as a function of doping. Conducting polymer actuators can provide more than an order of magnitude advantage over piezoelectric polymers regarding achievable dimensional changes, electrically generated stresses, and the work density per cycle. Using very thin films or fibers to minimize diffusion distances, cycle times of less than 100 ms and device lifetimes of above 106 cycles should be feasible for microactuators. Additionally, the conducting polymer actuators can operate at voltages which are about an order of magnitude lower than for piezoelectric actuators or electrostatic microactuators. Energy efficiencies, cycle times, and cycle lifetimes are, however, inherently much lower than for piezoelectric polymers.