Enhanced directional acoustic sensing with phononic crystal cavity resonance

This letter reports a phononic crystal (PnC) cavity resonance device to realize an enhanced directional acoustic sensing. The acoustic cavity in the PnC device is designed with a line defect produced by replacing a line array from a perfect PnC. The line-defect PnC will make a defect band related to the cavity resonance within the perfect PnC band gap range. The design enhances the input sound wave at the resonance frequency of the acoustic cavity under the normal incidence, which produces an enhanced direction-sensitive response. The proposed device shows desirable directional acoustic sensing property, and the sensing frequency can be decreased by enlarging the effective refractive index of the acoustic cavity. The PnC cavity resonance devices present broad application prospects in weak signal detection and sound source localization.