Proposal Number: ECS-9523978 Principal Investigator: Shrivinas Joshi Title: Reflection of ultrasonic lamb waves: theory and applications In this research, theoretical and experimental research into ultrasonic Lamb waves, which are elastic waves propagating in plates of finite thickness, is proposed. Recently Lamb wave devices have been fabricated on plates that are thinner than one micron (including work by the PI). Waves propagating in such thin structures have a number of attractive properties for use in physical, chemical and biological sensors. Lamb waves also can provide a convenient tool for measuring the elastic properties of self-supporting thin films and microminiature mechanical structures. In this work, Lamb wave reflections will be particularly investigated. The reflection analysis will consider three types of discontinuities: thin conducting strips, mass loading strips and etched grooves. The information obtained from this work will be used to develop Lamb wave resonators, unidirectional transducers and low loss delay lines. These devices will be designed and fabricated and their performance compared with the theoretical calculations. The combined theoretical/experimental investigations are both fundamental and thorough and should result in advances applicable to the general field of elastic-wave microsensors.
