Ionic polymer–metal composite (IPMC) are synthetic composite materials that display artificial muscle behaviour under an applied voltage. IPMCs are composed of an ionic polymer like Nafion or Flemion whose planar surfaces are coated with conductors such as platinum or gold. Under an applied voltage (1–5 V), ion migration and electrostatic repulsion result in a bending actuation. IPMCs are a type of electroactive polymer.
Alternately, IPMCs act as a smart material, as applying a mechanical force to the substance will result in a proportional voltage being applied onto the surface.
Bending actuators have seen limited application due to integration into larger devices or stronger actuators. Other limitations include the requirement to maintain ion mobility through hydration or other fluids. Higher voltages result in larger actuations, but voltages above 1.23V will result in electrolysis of water, limiting the useful voltage range.