Electroactive polymer actuators and sensors

Polymers are highly attractive for their inherent properties of mechanical flexibility, light weight, and easy processing. In addition, some polymers exhibit large property changes in response to electrical stimulation, much beyond what is achievable by inorganic materials. This adds significant benefit to their potential applications. The focus of this issue of MRS Bulletin is on polymers that are electromechanically responsive, which are also known as electroactive polymers (EAPs). These polymers respond to electric field or current with strain and stress, and some of them also exhibit the reverse effect of converting mechanical motion to an electrical signal. There are many types of known polymers that respond electromechanically, and they can be divided according to their activation mechanism into field-activated and ionic EAPs. The articles in this issue cover the key material types used in these two groups, review the mechanisms that drive them, and provide examples of applications and current challenges. Recent advances in the development of these materials have led to improvement in the induced strain and force and the further application of EAPs as actuators for mimicking biologic systems and sensors. As described in this issue, the use of these actuators is enabling exciting applications that would be considered impossible otherwise.