A new design method for miniature dual-resonance photoacoustic structure based on piezoelectric ceramics slice

We report a new design method for miniature dual-resonance photoacoustic (PA) structure, mainly consisting of a miniature T-type PA cell and a piezoelectric ceramics slice. Both the T-type PA cell and the piezoelectric ceramics slice have the resonance frequencies, and the resonance frequencies of the T-type PA cell and the piezoelectric ceramics slice exhibit the same variation pattern with size. It provides support for the design of miniature photoacoustic sensors. As an example, we developed a miniature dual-resonance photoacoustic sensor, the resonance frequency of the miniature T-type PA cell is matched with the natural frequency of the piezoelectric ceramics slice to achieve double resonance of the acoustic signal. The volume of the designed photoacoustic structure is only about 3.75 cubic centimeters. The performance of this system was evaluated through Methane detection. Experimental results show good linearity, the linear fitting R square is 0.9988. The minimum detectable limit of CH4 is calculated to be 542 ppb with an integration time of 217 s according to the Allan-Werle deviation analysis. The performance demonstrated a great potential for the design of miniature photoacoustic sensors.