Fabrication of ionic polymer-metal composite actuators with durable and quality-enhanced sputtered electrodes

In this study, a sputter-based procedure was developed for fabricating IPMC's wrinkled metal stack electrodes. Micro-texturing pre-treatments such as sandblasting and manual sandpapering followed by plasma treatment were individually used to wrinkle the surfaces of the Nafion membranes and to enhance the adhesion between membranes and sputtered electrodes. It was analytically indicated that increasing surface roughness increases the endurance of electrodes against the tensile stress. The effects of pre-treatment processes on the mechanical properties of the Nafion membranes and strength of the electrodes were investigated by means of the tensile test and theoretically discussed. The results show that micro-texturing of the surface of the membrane, resulting in a decrease in the elastic modulus and an increase in the yield stress. The surface roughening by sandblasting technique followed by plasma treatment before the sputtering process resulted in high-quality wrinkled electrodes, which can easily tolerate tensile strain caused by volume expansion of Nafion or IPMC bending, and significantly reduce cracks and prevent electrodes peeling off phenomenon. The proposed IPMC manufacturing approach is short, low cost, controllable, and reproducible. Investigation of the electromechanical performance of the IPMC actuator exhibits an average bending deformation of 115 degrees and an average blocking force of 75 mN under a driving voltage of 5 V.