Modelling, simulation and fabrication of surface acoustic wave motors employing dual friction-drive

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Surface acoustic wave (SAW) devices are widely used in sensors, actuators, filters, and telecommunication systems. SAWs are elastic waves launched on a piezoelectric substrate when an electrical signal is applied to metallic comb-like electrodes called as interdigital transducers (IDTs) patterned on the surface of the substrate. A SAW motor consists of a piezoelectric substrate with IDTs as the stator that generates Rayleigh SAW on its surface and displaces a movable part called as a slider placed in contact with the substrate. The operation of a SAW linear motor is based on the frictional drive generating high tangential force on the slider at the contact points with the stator, as the SAW travels on the surface of the stator.Conventionally the slider in a SAW motor is held tightly in contact with the surface of the stator and the preload is applied from the top through a lubricated guide rail to reduce friction at the top side of the slider while increasing friction between the stator and the bottom surface of the slider. To achieve the conflicting friction-related requirements at the two sides of the slider, normally heavy and bulky lubricated guide rails are used causing a major impediment in the commercialization of SAW motors. The research work presented in the thesis proposes a dual friction-drive (DFD) technique where an additional stator replaces the bulky guide rail to drive the slider from two sides and greatly simplifies the operating mechanism.
Supervisor: Harshal B. Nemade