Topological interface states in solid/liquid phononic crystal waveguides and sensing applications

Abstract

Topologically protected states in phononic crystals provide a new avenue to design robust acoustic devices as they are immune to structural imperfections or defects. In this work, the topological characteristics of solid/liquid phononic waveguides are investigated numerically using the finite element approach. Both the topologically trivial and non-trivial phononic crystals can be obtained by varying their geometry and hence are used for the construction of the phononic crystal structure that possesses the topological interface state. Furthermore, the wave barriers are designed by using another kind of PCs with a complete band gap, which can reduce the negative effect of acousto-structural interaction at the waveguide boundaries. The topological interface state is employed for the detection of sound velocity of the mixtures of water and 1-propanol. Importantly, the sensing quantities of the topological phononic crystal sensor are robust against introduced structural perturbations.