Melchiorre Luigi, Thottoli Ajmal, Vorobev Artem S, Menduni Giansergio, Sampaolo Angelo, Magno Giovanni, O'Faolain Liam, Spagnolo Vincenzo
PolySenSe Laboratory, Physics Department, Polytechnic University of Bari, Via G. Amendola 173, 70125 Bari, Italy.
nanoPhotonics and Electromagnetics Group, Electrical and Information Engineering Department, Polytechnic University of Bari, Via E. Orabona 4, 70125 Bari, Italy.
Sensors (Basel). 2025 Jun 11;25(12):3663. doi: 10.3390/s25123663.
This work demonstrates an ultra-compact optical gas-sensing system, consisting of a pigtailed laser diode emitting at 1392.5 nm for water vapor (HO) detection, a silicon nitride (SiN) optical waveguide to guide the laser light, and a custom-designed, low-frequency, and T-shaped Quartz Tuning Fork (QTF) as the sensitive element. The system employs both Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) and Light-Induced Thermoelastic Spectroscopy (LITES) techniques for trace gas sensing. A 3.8 mm-wide, S-shaped waveguide path was designed to prevent scattered laser light from directly illuminating the QTF. Both QEPAS and LITES demonstrated comparably low signal-to-noise ratios (SNRs), ranging from 1.6 to 3.2 for a 1.6% indoor HO concentration, primarily owing to the reduced optical power (~300 μW) delivered to the QTF excitation point. These results demonstrate the feasibility of integrating photonic devices and piezoelectric components into portable gas-sensing systems for challenging environments.
这项工作展示了一种超紧凑型光学气体传感系统，它由一个尾纤式激光二极管组成，该激光二极管发射1392.5 nm波长的光用于检测水蒸气（HO），一个氮化硅（SiN）光波导用于引导激光，以及一个定制设计的低频T形石英音叉（QTF）作为敏感元件。该系统采用石英增强光声光谱（QEPAS）和光致热弹性光谱（LITES）技术进行痕量气体传感。设计了一条3.8毫米宽的S形波导路径，以防止散射激光直接照射到QTF上。对于1.6%的室内HO浓度，QEPAS和LITES的信噪比（SNR）都相对较低，范围在1.6到3.2之间，这主要是由于传递到QTF激发点的光功率降低（约300 μW）。这些结果证明了将光子器件和压电组件集成到适用于具有挑战性环境的便携式气体传感系统中的可行性。
