Soft-film dynamics of SH-SAW sensors in viscous and viscoelastic fluids

Journal article, 2016

We theoretically investigate surface acoustic waves with horizontal polarization (SH-SAWs) propagating in a three-layer system consisting of an elastic substrate and two viscoelastic overlayers. For the limiting case of an acoustically thin middle layer and an infinite top layer, we derive analytical expressions for the phase velocity shift and the wave attenuation. These expressions demonstrate the importance of taking into account the viscoelastic coupling between the two overlayers. Numerical calculations using a combined Maxwell/Voigt scheme confirm our analytical results and also indicate that it is possible for viscoelasticity to cause SH-SAWs to vanish.