Fast contracting polypyrrole actuators

Conducting polymer-based actuators are capable of producing at least 10 times more force for a given cross-sectional area (active stress) than skeletal muscle, and potentially 1000 times more, with strains typically between 1% and 10%. Low operating voltages make them particularly attractive for use in micro-electromechanical systems, in place of electrostatic and piezoelectric actuators. A drawback of conducting polymer actuators is their relatively slow speed, and hence low power-to-mass ratio. In this paper, shaped voltage pulses are applied to generate strain rates of up to 3% s−1, with peak power to mass ratios of 39 W kg−1 of polymer, nearly matching mammalian skeletal muscle. Results are obtained from polypyrrole linear and bilayer actuators and employ both liquid and gel electrolytes.