E-Type Resonant Cell Based Photoacoustic Sensor for Flowing Gas Measurement

Abstract

An E-type resonant cell based photoacoustic gas analyzer with fast response has been proposed for flowing gas measurement. The proposed sensor integrates diffusion micropores and a silicon cantilever beam to enhance gas exchange efficiency and sensitivity. The resonant tube is completely embedded in the buffer chamber and two diffusion holes with a radius of 250 μm are designed to achieve miniaturization and accelerate the gas response speed, respectively. This design addresses the trade-off between flow measurement noise and response time observed in conventional T-type photoacoustic cells. Simulations and experiments demonstrate that the response time is reduced from 359 s (without micropores) to 22 s (with micropores). The experiment analyzed the influence of different flow rates on the gas diffusion time and flow noise of the E-type photoacoustic cell with micropores. At an integration time of 1 s, the sensor achieves a detection limit of 48.7 ppb for C2H2 and a normalized noise equivalent absorption (NNEA) coefficient of 2.9×10-9 cm-1·W·Hz-1/2.

Keywords: trace gas detection, E-type resonant cell, Flowing gas measurement, Diffusion micropores