A novel fabrication of ionic polymer–metal composite membrane actuator capable of 3-dimensional kinematic motions

Ionic polymer–metal composites (IPMCs) are one type of wet electroactive polymers that show promising actuating properties in many bio-inspiring underwater robotic applications. In these applications, 3-dimensional kinematic motions are desirable to generate high efficient thrust and maneuverability. However, traditional IPMCs are limited in being only able to generate bending motion. In this paper, a novel synthesis technique is developed to fabricate a hybrid IPMCmembrane actuator capable of generating 3-dimensional (3D) kinematicmotions. The actuator consists of separated IPMCbeams bondedwith a soft polydimethylsiloxane (PDMS)membrane. By controlling each individual IPMC beams, we can generate complex 3Dmotions such as oscillation and undulation. IPMC beams are cut from one sheet of IPMC, which is fabricated through chemically plating platinum electrodes on a Nafion film. A multiple plating process is used to enhance the conductivity of the electrodes, which leads to better actuation performance of IPMC. An assembly based fabrication process is adopted to bond the IPMC actuators with PDMS gel using two CNC-machined molds. Then the PDMS is cured at room temperature to form an actuating membrane. Overall this novel synthesis technique is cost effective and less time-consuming compared to existing strategies. The characterization of the actuating membrane has shown that the maximum twist angle can reach up to 15◦, the flapping deflection can reach up to 25% of spanwise length, the tip force can reach up to 0.5 g force, and the power consumption is below 0.5W. The first application of this novel membrane actuator is in the design of a free-swimming robotic batoid ray. The robot consists of two membranes functioning as artificial pectoral fins. Experimental results show that the robot is capable of free swimming with low power consumption. © 2011 Elsevier B.V. All rights reserved.