Solid-fluid interaction in a pillar-based phononic crystal

In this paper, we investigate the wave dispersion of two dimensional pillar-based phononic crystal surrounded in liquid medium. An unit cell structure with reduced pillar height (hp/a)=0.5 and reduced radius (rp/a)=0.3 is simulated using Finite Element Method. The geometrical parameter is chosen to demonstrate a local resonance mechanism that allow the confinement of elastic energy at the interface between the solid and the fluid. In order to identify the energy distribution, we represent the eigenmode at high symmetry (point X) in the first Brillouin zone. The decreasing trend of frequency is also boosted with the increase of pillar height. From the total displacement, the energy is mostly located inside the pillar and only a small value of displacement is present in the substrate. The results from this study could be useful for microfluidic and lab on chip application. We believe that the integration of pillar based phononic crystal with microfluidic could become a powerful tool in the sensor and actuator application for chemical and biological application.