Design, fabrication and testing of piezoelectric polymer PVDF microactuators

Piezoelectric polymers are increasingly considered as favorable materials for microactuator applications due to their fast response, low operating voltages and greater efficiencies of operation. However, the difficulty Of forming Structures and shapes has so far limited the range of mechanical design. In this work, the design and fabrication of a unimorph piezoelectric cantilever actuator using piezoelectric polymer polyvinylidene fluoride (PVDF) with an electroplated layer of nickel iron (permalloy) alloy is described. The modeling and simulation of the composite cantilever was performed using CoventorWare to optimize the design parameters in order to achieve large tip deflections. These simulation results indicated that the thicknesses of both the piezo and non-piezo layers of the composite cantilever affect the magnitude of deflection of the cantilever. It was shown that the tip deflection of such a cantilever with a length of 5 film and a width of I film can reach up to 70 mu m, when simulation was carried Out using a 28 mu m thick PVDF layer at a non-piezo layer thickness of 5 A PVDF polymer cantilever is fabricated Using a simple Punching technique based oil rnicroembossing. The permalloy layer was electroplated on one side of the PVDF to form a composite cantilever. The tip deflection of the cantilever was observed and measured Under an optical microscope. The experimental results showed deflection values which are 20% less than those predicted by the Simulation and analytical results. The thickness non-uniformity, residual stresses and possible difference in Young's modulus values of the bulk material to that of electroplated permalloy film are identified as some of the potential issues that might have caused this difference.