An ionic liquid-based actuator as a humidity sensor

The ionic electromechanically active polymer actuators with ionic liquid electrolytes working in air also respond to ambient relative humidity. The physicochemical parameters, especially viscosity and conductivity, of ionic liquids are strongly dependent on temperature as well as on their water content. By measuring the impedance between the actuator electrodes, the relative humidity value can be extracted from the signal. The sensing actuator has the ability of converting electric energy into mechanical work and additionally to sense the parameters of the surrounding environment.