Sensitive and Selective Photoacoustic Gas Sensor Suitable for High-Volume Manufacturing

Abstract

Sensitive and selective gas measurements are crucial for a large variety of applications. This paper describes the manufacturing and characterization of a photoacoustic gas sensor system. The system is based on a pressure sensor element with a sensitivity of 10 V/V/Pa. To demonstrate and evaluate the concept, 12 prototypes for measuring CO 2 have been manufactured and characterized. Detection limits ranging from 92 ppm to below 6 ppm CO 2 were obtained with a path length of 10 cm, depending on the measurement time and photoacoustic cell design. Measurements showed no cross-sensitivity towards CO, CH 4 , or humidity in any of the sensors. The temperature drift of the uncompensated raw signal of two sensor designs was below 117 ppm CO 2 in the range from 25 C to 50 C.Karl-Heinz Suphan began his career in 1981 as Engineer for R&D of hybrid circuits. In 1992, he joined Micro-Hybrid Electronic GmbH, Hermsdorf, Germany, and realized different projects in special applications of hybrid thickfilm technology. In 2000 he became a Senior Project Manager R&D. In this role, he is responsible for customer specific developments and technological projects.Dag T. Wang received the Ph.D. degree from the Norwegian University of Science and Technology in 1997 for work on disorder in semiconductors.He is currently a Chief Scientist at the Department of Microsystems and Nanotechnology at SINTEF, Oslo, Norway, specializing in design and fabrication of MEMS-based sensors. fields of expertise are within microsystem technology (MST), MEMS design with a special focus on gas sensor, bioMEMS, and fingerprint sensors. He is currently the CTO of the Norwegian company IDEX ASA supplying fingerprint sensor technology, and he holds a part-time adjunct professor position at NTNU.

Photoacoustic-Based Gas Sensing: A Review

“…Additionally, more companies have since developed their own solutions based on similar principles. With the emergence of microsystems technology, efforts have begun to miniaturize the URAS setup [47][48][49]. To this end, simulations of the sensitivity function of standard NDIR and photoacoustic NDIR underscore the potential for miniaturization [50] and experimental data does support this [51].…”

Investigating flexible feeding effects on the biogas quality in full‐scale anaerobic digestion by high resolution, photoacoustic‐based NDIR sensing

“…Modulation of the light source leads to the exiting soundwave whose amplitude is related to the amount of target gas in the measurement channel. About a decade ago, the first attempt to miniaturize this simple concept did use a micro-electro-mechanical system pressure sensor to gauge the light intensity of a thermal emitter [22], and since then different combinations of various types of broad band light sources and devices for determining the photoacoustic signal have been developed [23][24][25][26][27][28][29][30][31]. While the use of lasers in combination with acoustic resonators in setups of direct photoacoustic spectroscopy allow for ultra-sensitive trace gas detection, the use of such devices outside the laboratory is challenging [32][33][34][35][36].…”

Gas sensors for climate research

“…The working principle of the detector is based on the photoacoustic effect, which is why the LED intensity I 0 ( ν) has to be intensity modulated in order to trigger a photoacoustic signal in the detector (Scholz et al, 2017;Scholz and Palzer, 2016). The strength of the detector signal depends on the spectral overlap of the incident radiation at the detector and the absorption characteristics of the detector which Figure 2.…”

“…An early setup to miniaturize the URAS was demonstrated about a decade ago using pressure sensors to gauge the light intensity (Schjølberg-Henriksen et al, 2008). Since then, both thermal emitters as well as light-emitting diodes (LEDs) have been used in combination with gas-based detectors to build gas sensors (Bierer et al, 2018;Knobelspies et al, 2016;Köhring et al, 2015;Kuusela et al, 2009;Scholz et al, 2017;Scholz and Palzer, 2016;Wittstock et al, 2017;Uotila, 2007;Lindley et al, 2007;Chen et al, 2005;Karioja et al, 2010) for various applications. Additionally, we present a simulation comparing the sensitivity of standard NDIR and photoacoustic-based NDIR to highlight the potential for miniaturization when using a gas-based detector.…”