Influence of Humidity and Actuation time on Electromechanical Characteristics of Ionic Polymer-Metal Composite Actuators

This paper experimentally investigates the effects of humidity and actuation time on the electromechanical properties of Ionic Polymer-Metal Composites (IPMC) to improve the practical applications of using the IPMCs as soft biomimetic sensors and actuators. The experiments are conducted in both the open atmosphere (uncontrolled environment at room temperature) and inside a controlled environmental chamber under different input voltages (in term of wave shape, value, and frequency). Results show that the IPMC's electromechanical properties, namely the deformation capacity and electrical resistance, highly depend on the water content (in the IPMC strip and environment) and the duration of actuation. The Deflection and current of the tested IPMC samples can be represented by an exponential time function were an exponent value decreases with increasing the humidity. IPMC deformation capacity decreases while material electrical resistance increases during activation session. Increasing relative humidity to more than 50% reduces the drying effect on the IPMC deformation capacity and resistance. Also, the IPMC material shows a relaxation behavior for a step voltage input, which can be related to the back immigration of the hydrated cations from the anode to the cathode due to higher pressure at the anode side of the IPMC strip. (C) 2018 The Authors. Published by Elsevier B.V.