Characterization and modelling of a conducting polymer muscle-like linear actuator

The demand for actuators featuring biomimetic properties, such as linearity, high power density and compliance, is growing in microrobotics and bioengineering. In the present paper a novel linear actuator is presented. It exploits the electromechanochemical phenomena of -electron conjugated conducting polymers, occuring when ionic species are exchanged with the surrounding medium, i.e. solid or liquid electrolyte. In our experiments, a polypyrrole film doped with benzensulphonate anions is considered as the conducting polymer and a liquid electrolyte bath as the ionic reservoir. The actuating properties of the material are investigated and quantified in terms of both isotonic displacement and isometric developed force. A lumped parameter, muscle-like model of the system is proposed and verified with respect to the experimental data. The results of the electromechanical characterization and the goodness of fit of the model provide favourable indications for the utilization of the material as an effective muscle-like linear actuator, once the response time is decreased by means of a suitable scaling down of the film thickness.