Enhanced control and stability of polypyrrole electromechanical actuators

The practical application of polypyrrole (PPy) actuators requires a stable strain response and a high degree of reproducibility from sample to sample. The use of symmetrical voltage cycling to control the actuation of polypyrrole is shown to lead to a slow net oxidation of the polymer after several tens of cycles. The result is a slow deterioration in the actuation strain. The use of current pulsing reduces this problem and gives a more stable strain response. Current pulsing in combination with an ionic-liquid (IL) electrolyte allowed a strain of 3% to be achieved repeatably for many different samples for at least 100 cycles. (C) 2003 Elsevier B.V. All rights reserved.