Perturbation method for analyzing mass sensitivity of planarmultilayer acoustic sensors

摘要

A perturbation method is developed to analyze the mass loadingnsensitivity of planar composite acoustic gravimetric sensors. Thensensitivity formulas are obtained in explicit forms for the two lowestnsagittal (D1 and D2) modes, the lowest shearnhorizontal (SH0) mode and high-order SHm modes inna two-layer isotropic composite plate sensor. The composite platenconsists of a plate of thickness b coated by a film of thickness h onnwhich the mass loading layer of infinitesimal thickness is deposited.nThis coating can be a chemically selective film which is assumed to benacoustically thin (h<Λ), where Λ is the acousticnwavelength. For Love modes supported by a film coated on a semi-infinitensubstrate and for Rayleigh modes on a semi-infinite substrate, thensensitivity formulas are expressed in analytical form. These formulasnspecify the contribution of each material parameter in the substrate andnfilm, and of the elasticity of the mass loading layer for each planarnsensor, and provide a general guide for enhancing the sensor sensitivity