Analytical modeling of a segmented unimorph actuator using electrostrictive P(VDF-TrFE)copolymer**Presented in part at the ASME Design Engineering Technical Conferences, Symposium onMechanisms and Devices for Medical Applications, Pittsburgh, PA, September, 2001 and atthe SPIE 8th International Symposium on Smart Structures and Materials, NewportBeach, CA, March, 2001.

Abstract

An analytical model is developed for a segmented unimorph actuator consisting ofelectrostrictive P(VDF-TrFE) copolymer. The segmented actuator consists of individuallycontrolled segments of the active polymer so that varying curvature along the length can beachieved. The analytical model incorporates large deflections and can be used to predictthe free deflection and blocked force along the length of the actuator. The targetapplication is active instruments for minimally invasive surgery (MIS), where steerable tooltips are needed to increase dexterity and provide nonlinear access. Results are presented toillustrate predicted free deflection and blocked force for various electric fields. Anoptimization procedure is also employed to design an actuator for maximum tip deflection,blocked force and out-of-plane stiffness. The predicted deflection performance of theoptimized design is shown to be suitable for application to minimally invasive surgery.