Huan Huiting, Sun Jialiang, Liu Lixian, Yue Ying, Zhang Xueshi, Zhang Le, Li Yifan, Zhang Lingmin, Zhang Yimeng, Xu Xuesen, Xu Huailiang, Mandelis Andreas
School of Optoelectronic Engineering, Hangzhou Institute of Technology and State, Key Laboratory of Electromechanical lntegrated Manufacturing of High-performance Electronic Equipment, Xidian University, Xi'an 710071, China.
School of Electronic Engineering, Xi'an Shiyou University, Xi'an 710065, China.
Anal Chem. 2025 Jul 15;97(27):14637-14648. doi: 10.1021/acs.analchem.5c02177. Epub 2025 Jun 27.
Dissolved gases in transformer oil are reliable indicators of operating conditions and fault types. Additionally, ambient water vapor can seriously affect the accuracy of photoacoustic dissolved gas analysis systems. Therefore, there is an urgent need for the development of the simultaneous detection of dissolved gases and water. A high-sensitivity, multiple-gas sensing system was developed by combining a differential photoacoustic cell and a water vapor fiber-optic sensor. The acoustic properties of the designed differential photoacoustic cell were analyzed through simulation and experimental validation for the differential and longitudinal modes, and the frequency difference between excitation and nonexcitation optical paths in the longitudinal mode was leveraged, achieving an amplitude response comparable to that of the differential mode. CH, CH, and CO measurements were performed at three resonance frequencies using two DFB and a QCL source. To monitor HO concentration and evaluate its effect on photoacoustic detection, a fiber-optic Fabry-Perot interferometer was developed using self-assembled microspheres with high specific surface area, single-mode optical fibers, and concentric tapered capillary tubes. Water vapor adsorption on the microspheres altered the refractive index, and cavity-length demodulation was employed to analyze the interference spectra to obtain the water vapor concentration. The water optical sensor showed high sensitivity of ∼112 pm/% for HO detection. Experimental results demonstrated that the dual-mode multicomponent gas sensor can achieve detection limits of 1.15, 241.07, and 367.32 ppb for CO, CH, and CH, respectively, with corresponding normalized equivalent noise absorption coefficients of 1.53 × 10 cm·W·Hz, 4.56 × 10 cm·W· Hz, and 3.75 × 10 cm·W·Hz.
变压器油中的溶解气体是运行状况和故障类型的可靠指标。此外，环境水蒸气会严重影响光声溶解气体分析系统的准确性。因此，迫切需要开发同时检测溶解气体和水的方法。通过将差分光声池和水蒸气光纤传感器相结合，开发了一种高灵敏度、多气体传感系统。通过对差分模式和纵向模式的模拟和实验验证，分析了所设计的差分光声池的声学特性，并利用纵向模式下激发光路和非激发光路之间的频率差，实现了与差分模式相当的幅度响应。使用两个分布反馈激光器（DFB）和一个量子级联激光器（QCL）源在三个共振频率下进行了CH₄、C₂H₄和CO的测量。为了监测H₂O浓度并评估其对光声检测的影响，使用具有高比表面积的自组装微球、单模光纤和同心锥形毛细管开发了一种光纤法布里-珀罗干涉仪。微球上的水蒸气吸附改变了折射率，并采用腔长解调来分析干涉光谱以获得水蒸气浓度。该水光学传感器对H₂O检测显示出约112 pm/%的高灵敏度。实验结果表明，该双模多组分气体传感器对CO、CH₄和C₂H₄的检测限分别可达1.15、241.07和367.32 ppb，相应的归一化等效噪声吸收系数分别为1.53×10⁻⁶ cm·W⁻¹·Hz⁻¹/²、4.56×10⁻⁶ cm·W⁻¹·Hz⁻¹/²和3.75×10⁻⁶ cm·W⁻¹·Hz⁻¹/²。
