A piezoelectric twisting beam actuator

We present a novel piezoelectric bulk-unimorph beam actuator that can be directly driven in twisting. The bulk-unimorph beam is driven by interdigitated electrodes (IDEs), deposited over its top and bottom surfaces. These IDEs are oriented at 45° relative to the beam axis, and they are used for both poling and actuation. When subjected to a driving voltage, the IDEs induce both axial and shear stresses in the vicinity of the surface over which they are deposited. These stresses give rise to both internal bending and internal torsion moments. When one set of electrodes, either on the top or the bottom surface, is used to drive the lead zirconate titanate beam, a coupled bending/twisting response is induced. However, when both the top and bottom electrodes are used, we can achieve either a pure torsion mode or a pure bending mode, with no cross coupling, depending on the driving scheme.