B1.4 A Humidity-independent Photoacoustic Sensor

Event
SMSI 2021
2021-05-03 - 2021-05-06
digital
Band
SMSI 2021 - Sensors and Instrumentation
Chapter
B1 Gas Sensors I
Author(s)
E. Ambra, G. Pang, C. Haish - Technical University of Munich, Munich (Germany)
Pages
109 - 110
DOI
10.5162/SMSI2020/B1.4
ISBN
978-3-9819376-4-0
Price
free

Abstract

Photoacoustic spectroscopy is routinely used to characterize absorption of gas and aerosols in various environments. To obtain accurate absorption measurements in atmospheric science, where variations in humidity exist, the photoacoustic signal’s dependence from relative humidity must be investigated in-depth. For this purpose, we used a resonant photoacoustic cell embedded with a piezoMEMS microphone, which is insensitive to humidity. We scanned the light modulation frequency around the theoretical resonance value and acquired the microphone signal through a lock-in amplifier. From the results, we can affirm that the overall photoacoustic sensor response is independent of the humidity parameter only if we consider the photoacoustic signal amplitude at the exact resonance frequency, which shifts with humidity.

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