Restraining IPMC Back Relaxation in Large Bending Displacements: Applying Non-Feedback Local Gaussian Disturbance by Patterned Electrodes

Despite advantages and promising features of ionic polymer-metal composite (IPMC), this smart material has some drawbacks that should be eliminated as much as possible for improving the IPMC performance. One of the most important drawbacks is the back relaxation (BR). When a step input voltage is applied to the IPMC, it bends toward the anode. The BR is the unwanted and slow bending of the IPMC back toward the cathode. Several techniques based on using a feedback control loop have been proposed for eliminating the BR effect. However, these techniques are effective only when the bending displacement of the IPMC is small. In this paper, we propose a nonfeedback method for restraining the IPMC BR effect even in large bending displacement. The proposed technique is based on the fast reciprocating motions of free water molecules in Nafion membrane between the anode and the cathode. For this purpose, we have used a local Gaussian disturbance in a specifically patterned IPMC. We have described our idea conceptually and we have validated it by several experimental results.