Trace Acetylene Gas Detection Based on a Miniaturized Y-Sphere Coupled Photoacoustic Sensor.

In this work, a miniaturized Y-sphere coupled photoacoustic (YSCPA) sensor is proposed for trace CH gas detection. The cavity volume of the designed YSCPA sensor is about 0.7 mL. The finite element method (FEM) has been performed to analyze the comparative performance of the YSCPA sensor and T-type PA sensor, indicating that the first-order resonance frequency (FORF) of the newly proposed YSCPA sensor has been reduced by half while the PA signal has been improved by a factor of 3 compared to the T-type PA sensor. CH is employed as a target gas to test the performance of the YSCPA sensor. The experimental test results show that the response time of the gas is 26 s. The minimum detection limit (MDL) reaches 189 ppb at a lock-in integration time of 1 s. By extending the lock-in integration time to 100 s, the MDL of the designed PA sensor is reduced to 18.1 ppb. The designed YSCPA sensor has the advantages of small size, low gas consumption, simple structure, and high sensitivity, which is expected to be an effective solution for rapid and real-time monitoring of dissolved CH gas in transformer oil.