Design and realization of electroactive polymer actuators for transparent and flexible haptic feedback interfaces

This article deals with the development of force actuator buttons for haptic feedback applications. Finite Element Method (FEM) models were used to design high performances piezoelectric actuators able to promote force restitution that can be sensed by a finger. We present first a comparison between analytical modeling and displacement measurement of cantilevers based on electroactive polymer (EAP) actuator. This calibration step leads to model optimization, through material data base precision. Then force buttons were studied by adjusting the ratio between actuator and membrane radius in order to obtain the largest force restitution, at least 50 mN/cm2. It has been shown that an actuator radius equal to 60% of the membrane radius exhibits the best performances. We also studied actuator stacking in order to increase the force restitution that can be promoted by a circular button. FEM models predict that a stack of 20 actuators is needed to match the aimed force restitution at 50V, however when the voltage is increased to 200V, only 5 actuators stacked are necessary.