Free Oscillation Frequency of IPMC Actuator as an Indicator of its Water Content

Properties of ionic polymer-metal composite (IPMC) actuator deteriorate during operation. Displacements become smaller and the resonance frequency increases. It happens because IPMC actuator dries out during operation. This effect takes place due to Joule heating and evaporation from surface of actuator. It is well known that the resonance frequency depends on Young's modulus and material density (or actuator's weight). It was shown experimentally that the Young's modulus has greater impact on the resonance frequency then material density during a process of drying. Also, a measurement bench and technique were developed.