Silicon acoustic waveguide based on locally resonant phononic crystal

This paper demonstrates a phononic crystal based silicon acoustic waveguide for the controllable propagation of Lamb waves in several MHz range. Different from the former phononic crystal applied in MEMS, which is based on Bragg scattering theory, the phononic crystal employed in this paper is based on locally resonant theory, which could provide better confinement of the acoustic waves. The silicon waveguide was fabricated by micro machining process, and tested by a combination of the fluid coupling method and Laser Doppler Vibrometer. The experimental result shows a good agreement with our theory prediction, that the designed locally resonant phononic crystal could effectively confine the elastic waves with selected frequency range in the guiding zone. The locally resonant phononic crystal demonstrated in paper is a good candidate for the control of acoustic waves propagating in MEMS.