A silicon micromechanical resonator with capacitive transduction for enhanced photoacoustic spectroscopy

This paper presents the design of a silicon micromechanical resonator with capacitive transduction for a gas sensor based on photoacoustic spectroscopy. It overcomes problems imposed by opposite physical trends originating from the sensor’s working principles. The capacitive transduction mechanism i...

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Bibliographic Details
Published inSensors and actuators. B, Chemical Vol. 353; p. 131070
Main Authors Trzpil, Wioletta, Charensol, Julien, Ayache, Diba, Maurin, Nicolas, Rousseau, Roman, Vicet, Aurore, Bahriz, Michael
Format Journal Article
LanguageEnglish
Published Lausanne Elsevier B.V 15.02.2022
Elsevier Science Ltd
Elsevier
Subjects
Capacitive transduction
Damping
Engineering Sciences
Excitation
Gas sensor
Gas sensors
MEMS
Micro and nanotechnologies
Micro-mechanical resonator
Microelectronics
Optics
Photo-acoustic
Photoacoustic spectroscopy
Photonic
Resonators
Silicon
Spectroscopy
Spectrum analysis
Spectroscopy
Photo-acoustic
Capacitive transduction
Gas sensor
MEMS
Micro-mechanical resonator
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Summary:This paper presents the design of a silicon micromechanical resonator with capacitive transduction for a gas sensor based on photoacoustic spectroscopy. It overcomes problems imposed by opposite physical trends originating from the sensor’s working principles. The capacitive transduction mechanism is considered incompatible with the photoacoustic gas detection as it reduces the mechanical displacement by a damping effect, thus decreasing the sensitivity. This occurs because the same part serves two functions: photoacoustic excitation and capacitive transduction. The suggested approach in this study focuses on the spatial separation of these two functions. We propose the first reported mechanical microresonator for photoacoustic gas sensing, which decouples photoacoustic excitation and capacitive transduction. The design has been modeled, fabricated, characterized, and compared with the on-beam Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) technique, a reference for compact and selective gas sensors. The performed photoacoustic measurement has been realized on calibrated concentrations of methane. For a 1 s integration time in first harmonic detection, we obtained a limit of detection (LOD) of 667 ppmv for silicon microresonator. In comparison to on-beam QEPAS technique, we obtained LOD of 163 ppmv, which constitutes a factor 4 between QEPAS and MEMS. The conditions for both experiments were the same.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2021.131070