The effect of surface-electrode resistance on the performance of ionicpolymer-metal composite (IPMC) artificial muscles

Abstract

Reported in this study are the effects of the surface-electroderesistance on the performance of ionic polymer-metal composite (IPMC)artificial muscles. The IPMC artificial muscles manufactured in this study iscomposed of a perfluorinated ion-exchange membrane, platinum composited byusing a chemical processing technique that employs a platinum salt andappropriate reducing agents. Furthermore, the IPMC artificial muscles wereoptimized for producing improved forces by changing multiple processparameters including the time-dependent concentrations of the salt andreducing agents. However, the analytical results confirmed that the platinumelectrode is successfully deposited on the surface of the material whereplatinum particles stay in a dense form that appears to introduce asignificant level of surface-electrode resistance. In order to address thisproblem, a thin layer of silver (or copper) was electrochemically deposited ontop of the platinum electrode to reduce the surface-electrode resistance.Actuation tests were performed for such IPMC artificial muscles under a lowvoltage. The test results show that the lower surface-electrode resistancegenerates higher actuation capability in the IPMC artificial muscles. Thisobservation is briefly discussed based on the role that the equivalent circuitfor the IPMC plays and a possible electrophoretic cation-transport phenomenonunder the influence of an electric field.