Electroactive polymer (EAP) actuators—background review

Certain polymers can be excited by electric, chemical, pneumatic, optical, or magnetic field to change their shape or size. For convenience and practical actuation, using electrical excitation is the most attractive stimulation method and the related materials are known as electroactive polymers (EAP) and artificial muscles. One of the attractive applications that are considered for EAP materials is biologically inspired capabilities, i.e., biomimetics, and successes have been reported that previously were considered science fiction concepts. Today, there are many known EAP materials. Some of the EAP materials also exhibit the reverse effect of converting mechanical strain to electrical signal allowing using them as sensors and energy harvesters. Efforts are made worldwide to turn EAP materials to actuators-of-choice and they involve developing their scientific and engineering foundations including the understanding of their operation principles. These are also involve developing effective computational chemistry models, comprehensive material science, and electro-mechanics analytical tools. These efforts have been leading to better understanding the parameters that control their capability and durability. Moreover, effective processing techniques are developed for their fabrication, shaping, electroding, and characterization. While progress have been reported in the research and development of all the types of EAP materials, the trend in recent years has been growing towards significant development in using dielectric elastomers.