Ionic polymer-metal composite as a new actuator and transducer material

Abstract

Ionic polymer-metal composites (IPMCs) are a unique polymer transducer that when subjected to an imposed bending stress exhibits a measurable charge across the chemically and/or physically placed effective electrodes of the electroactive polymer. IPMCs are also known as bending actuators capable of large bending motion when subjected to a low applied electric field (∼10 kV/m) across the metalized or conductive surface (Figure 6.1). The voltage found across the IPMC under an imposed bending stress is one to two orders of magnitude smaller than the voltage required to replicate the bending motion input into the system. This leads to the observation that the material is quite attractive by showing inclination for possible transduction as well as actuation [1-25]. In 1993, an IPMC was first reported as an active polymeric material by Oguro and his co-workers [21]. Since then, much attention has been given to IPMCs with the hope that they can be used as a soft actuator and sensor/transducer material for new opportunities in future engineering. IPMCs have been considered promising actuator materials, in particular for biorobotic applications. Part of what makes an IPMC so unique are its inherent transductive/sensing properties in addition to its actuation capabilities. Similar to piezo materials, IPMCs can show displacements under an applied electric field and can also engender a current from an imposed bending moment that is applied to the material. The voltage can be as high as in the 10's of millivolts range for larger imposed bending displacements. This makes IPMCs possibly effective for large motion sensor or damper applications if their behavior can be properly controlled.