The effect of surface-electrode resistance on the actuation of ionic polymer-metal composites (IPMCs) artificial muscles

In this work the effect of surface-electrode resistance on the actuation of ionic polymer-metal composites (IPMCs) artificial muscles is investigated. The as-received ion-exchange membrane (IEM) was platinum-composited by using a unique chemical processing technique that employs a platinum-salt and appropriate reducing agents. The IPMCs artificial muscles were optimized for producing maximum forces by changing multiple process parameters including time-dependent concentrations of the salt and reducing agents. The analytical results confirmed that the platinum electrode is successfully deposited on the surface of the IEM where platinum particles stay in a dense form that appears to introduce: a significant level of surface-electrode resistance. In order to address this problem, a thin layer of silver (or copper) was electrochemically deposited on top of the platinum electrode to reduce the surface-electrode resistance. Actuation tests were performed for such IPMC artificial muscles under a low voltage. Test results show that the lower surface-electrode resistance generates the higher actuation capability in the IPMCs artificial muscles. This observation is briefly discussed based on an equivalent circuit theory regarding the IPMC and a possible electrophoretic cation-transport phenomenon under the influence of an electric field.