In the last decade a new breed of polymer has emerged which responds to external electrical stimulation by displaying a significant shape or size displacement. These materials, known as electroactive polymers, or more commonly EAPs are now on the verge of many exciting applications.

EAPs have attracted much attention from engineers and scientists from diverse disciplines. In particular, researchers in the field of biomimetics (a field of study where robotic mechanisms are based on biologically-inspired models) find it foreseeable that these materials may be applied to mimic the movements of animals, insects and even human body parts (Figure 1).

Figure 1. Potential application for EAP in biomimetics.

Generally, EAPs have the ability to induce strains that are as high as two orders of magnitude greater than the movements possible with rigid and fragile electroactive ceramics (EACs). EAP materials have higher response speeds, lower densities and improved resilience when compared to shape memory alloys (SMAs). Limiting factors to EAPs are low actuation forces, mechanical energy density and lack of robustness. However, there have been reported successful applications in catheter steering elements, miniature manipulators, dust-wipers, miniature robotic arms and grippers.

There are two major categories that EAPs depending on their mode of activation mechanism, these include, electronic and ionic categories. Table 1, outlines the advantages and disadvantages of both types of EAPs.