Theory of Lamb Wave Transducers and Their Applications for Gas and Liquid Sensing

Theoretical basis of Lamb wave transducers (LWT) for gas and liquid sensing is developed systematically. Two basic types of transduction mechanisms, piezoelectric and electrostatic, are discussed. A model for capacitive LWTs with second-order bending mode excitation is further developed. A design with a 100 nm thick silicon plate shows GHz resonance frequency and zg mass resolution, which is comparable with nanomechanical resonators using cantilevers and doubly clamped beams.