Analytical modeling of a segmented unimorph actuator using electrostrictive P(VDF-TrFE) copolymer

An analytical model is developed for a segmented unimorph actuator consisting of electrostrictive P(VDF-TrFE) copolymer. The segmented actuator consists of individually controlled segments of the active polymer so that varying curvature along the length can be achieved. The analytical model incorporates large deflections and can be used to predict the free deflection and blocked force along the length of the actuator. The target application is active instruments for minimally invasive surgery (MIS), where steerable tool tips are needed to increase dexterity and provide nonlinear access. Results are presented to illustrate predicted free deflection and blocked force for various electric fields. An optimization procedure is also employed to design an actuator for maximum tip deflection, blocked force and out-of-plane stiffness. The predicted deflection performance of the optimized design is shown to be suitable for application to minimally invasive surgery.