A MECHANICAL MODEL FOR ENERGY-TRANSFER IN LINEAR ULTRASONIC MICROMOTORS USING LAMB AND RAYLEIGH-WAVES

This paper presents the theory, simulation results, and experimental s tudy of the slider displacement at nanometer scale in linear ultrasoni c micromotors using Lamb and Rayleigh waves, which can be used as micr oconveyers, To the authors' knowledge, this is the first attempt at de scribing analytically the energy transfer from the acoustic wave to th e slider. The model shows that the mechanism is sequential with altern ative phases of levitation and contact with step-like behavior of the slider velocity, To validate the model, microconveyers using Lamb and Rayleigh waves are fabricated, These waves are generated from interdig ital transducers with 10- and 20-MHz frequencies, respectively, which are the highest ones in ultrasonic micromotors, The control of motion is obtained by varying the duration of the driving signal applied acro ss interdigital transducers, The measured displacement varies from sev eral nanometers to several centimeters. A comparison between experimen tal and theoretical results shows a good agreement. This model gives a qualitative description of motion, In another way, it allows the dedu ction of key parameters for energy transfer, in order to improve the d esign of these micromotors so as to meet the requirements in nanotechn ology.