IES, University Montpellier, CNRS, 34090 Montpellier, France.
Sensors (Basel). 2021 Jul 26;21(15):5056. doi: 10.3390/s21155056.
In Quartz-Enhanced PhotoAcoustic Spectroscopy (QEPAS) gas sensors, the acoustic wave is detected by the piezoelectric Quartz Tuning Fork (QTF). Due to its high-quality factor, the QTF can detect very low-pressure variations, but its resonance can also be affected by the environmental variations (temperature, humidity, …), which causes an unwanted signal drift. Recently, we presented the RT-QEPAS technique that consistently corrects the signal drift by continuously measuring the QTF resonance. In this article, we present an improvement of RT-QEPAS to fasten the QTF characterization time by adding a passive electronic circuit, which causes the damping of the QTF resonance. The damping circuit is optimized analytically and through SPICE simulation. The results are supported by experimental observations, showing a 70 times improvement of the relaxation times compared to the lone QTF, which opens the way to a fast and drift-free QEPAS sensor.
在石英增强光声光谱（QEPAS）气体传感器中，声被压电石英音叉（QTF）检测到。由于其高品质因数，QTF 可以检测到非常低的压力变化，但它的共振也会受到环境变化（温度、湿度等）的影响，这会导致不必要的信号漂移。最近，我们提出了 RT-QEPAS 技术，通过连续测量 QTF 的共振来始终如一地校正信号漂移。在本文中，我们对 RT-QEPAS 进行了改进，通过添加一个无源电子电路来加快 QTF 的特性化时间，该电路会导致 QTF 共振的阻尼。阻尼电路经过了理论分析和 SPICE 模拟的优化。实验结果证实了这一点，与单独的 QTF 相比，弛豫时间提高了 70 倍，这为快速无漂移的 QEPAS 传感器开辟了道路。
