Direct Torsion of Bulk PZT Using Directional Interdigitated Electrodes

We present a bulk unimorph piezoelectric beam, which is directly actuated in a torsional mode. The direct torsion actuation is achieved by Interdigitated Electrodes (IDE), oriented at 45°relative to the beams axis. The IDE are deposited directly on a bulk piezoelectric plate, which serves as both the substrate and as the device layer. Elimination of a substrate layer solves the issues of residual stress and thermal expansion mismatch. In addition, the fact that all electrodes are deposited simultaneously over a single surface, simplifies fabrication to a two-mask process, and facilitates electrical connection to the electrodes. The bulk lead zirconate titanate (PZT) plate is etched using a cheap and simple sand-blasting process. We present proof-of-concept devices, and demonstrate direct torsion deformation of a cantilever beam.