Based on the elastic wave propagation theory, a dispersion equation for Lam
b waves in a thin anisotropic plate bordered with one viscous liquid layer
is derived. Viscosity-induced attenuation of the waves is discussed. Numeri
cal calculations show that resonance vibration of the liquid layer and the
plate may cause the changing of wave modes. The viscosity and the density s
ensing of Lamb-wave microsensors are both discussed in detail.