Weber C, Kapp J, Wöllenstein J, Schmitt K
Department of Microsystems Engineering-IMTEK, Laboratory for Gas Sensors, University of Freiburg, Georges-Koehler-Allee 102, 79110, Freiburg, Germany.
Fraunhofer Institute for Physical Measurement Techniques IPM, Koehler-Allee 301, 79110, Freiburg, Germany.
Photoacoustics. 2023 Apr 14;31:100495. doi: 10.1016/j.pacs.2023.100495. eCollection 2023 Jun.
Photoacoustic gas sensing is a method suited for the detection of radiation absorbing molecular species in the gas phase. Due to the backgroand-free detection, it has considerable benefits in the measurement of very low concentrations down to the parts-per-trillion range. Yet in resonant systems, the resonance frequency depends on several parameters like temperature or gas composition and therefore must be continuously determined. In the present work, we propose a new method of tracking the resonance frequency using a photoacoustic signal generated at the walls of the resonant cell. The method has been evaluated with two different photoacoustic setups intended for the detection of NO. We further propose an algorithm for finding the resonance frequency and evaluated the performance thereof. With this method, it is possible to detect the resonance frequency of a cylindrical and a dumbbell-shaped cell in less than two seconds and with an accuracy < 0.06% and < 0.2%, respectively.
光声气体传感是一种适用于检测气相中吸收辐射的分子物种的方法。由于无背景检测，它在测量低至万亿分之一范围的极低浓度时具有相当大的优势。然而，在谐振系统中，共振频率取决于几个参数，如温度或气体成分，因此必须不断确定。在本工作中，我们提出了一种利用谐振池壁产生的光声信号跟踪共振频率的新方法。该方法已通过两种用于检测一氧化氮的不同光声装置进行了评估。我们还提出了一种用于找到共振频率的算法并评估了其性能。使用这种方法，可以在不到两秒的时间内检测到圆柱形和哑铃形池的共振频率，精度分别<0.06%和<0.2%。
