Estimation of physical constants of silicon-based polymer thin films using surface acoustic waves and their application to liquid sensor

Physical constants of poly(di-methyl silane) are estimated from the characteristics of the surface acoustic wave (SAW) propagating along poly(di-methyl silane)/(128°rot.Y-X) LiNbO₃ structure. The values of c₁₁ and c₄₄ are estimated to be (5.9±0.9)×10¹⁰ and (1.2±0.3)×10¹⁰ N/m², respectively. Using the obtained stiffness constants and density of poly(di-methyl silane), the leaky SAW propagation character is estimated from the numerical calculation based on the first-principle-equations. As a result, it is found that liquid/polysilane/(128°rot.Y-X) LiNbO₃ structure is useful for estimating physical constants of the liquid loaded on the device surface, i.e., the surface of the polysilane thin film