Downsizing and Silicon Integration of Photoacoustic Gas Cells

Abstract

Downsizing and compatibility with MEMS silicon foundries is an attractive path towards a large diffusion of photoacoustic trace gas sensors. As the photoacoustic signal scales inversely with the chamber volume, a trend to miniaturization has been followed by several teams. We review in this article the approach initiated several years ago in our laboratory. Three generations of components, namely a 40 mm 3 3D-printed cell, a 3.7 mm 3 silicon cell, and a 2.3 mm 3 silicon cell with a builtin piezoresistive pressure sensor, have been designed. The models used take into account the viscous and thermal losses, which cannot be neglected for such smallsized resonators. The components have been fabricated either by additive manufacturing or microfabrication and characterized. Based on a compilation of experimental data, a similar sub-ppm limit of detection is demonstrated. All three versions of photoacoustic cells have their own domain of operation as each one has benefits and drawbacks, regarding fabrication, implementation, and ease of use.

Photoacoustic-Based Gas Sensing: A Review

“…While many efforts are aimed at improving sensitivity, the long-standing goal of miniaturization of these setups to make them portable is being pursued as well. In terms of miniaturization, 3-D printers and silicon technology have been used to build simpler and smaller setups with diminished performances but at much lower cost and requiring less infrastructure [88][89][90][91][92][93][94].…”

Programmable and Modularized Gas Sensor Integrated by 3D Printing

“…Weigl utilized a 3D-printed aluminum cell in a photoacoustic trace gas sensor to optimize light coupling while minimizing background signal generation, achieved through a specially designed cell structure and the incorporation of a spirally formed gas channel for gas heating prior to detection . Additionally, metal cells showed promise for photoacoustic gas cells, demonstrating high integration and practicality with customized structure designs . Given that sensor cells come into direct contact with gases, it is crucial to consider the corrosion resistance of the 3D printing materials, particularly when detecting corrosive target gases.…”

“…197 Additionally, metal cells showed promise for photoacoustic gas cells, demonstrating high integration and practicality with customized structure designs. 198 Given that sensor cells come into direct contact with gases, it is crucial to consider the corrosion resistance of the 3D printing materials, particularly when detecting corrosive target gases. In Bonilla-Manrique's work, the target gas was H 2 S, and a resonant gas cell was employed for a photoacoustic sensor.…”

Cantilever-enhanced photoacoustic spectroscopy for gas sensing: A comparison of different displacement detection methods

“…Lhermet et al reported a micro photoacoustic cell with integrated piezoresistive cantilever microphone [77] , [78] , [79] . This is the third-generation device of miniature photoacoustic components at CEA-LETI (a laboratory in French Atomic Energy and Alternative Energy Commission).…”

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Fig. 9 The photoacoustic sensor of CEA-LETI [79] . (a)Structure of the silicon-integrated sensor (left) and photo of the manufactured chip (right).

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