{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:48:49Z","timestamp":1760150929137,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2022,1,17]],"date-time":"2022-01-17T00:00:00Z","timestamp":1642377600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Baden-W\u00fcrttemberg Ministry of Science, Research and Art","award":["(funding programme Open Access Publishing)"],"award-info":[{"award-number":["(funding programme Open Access Publishing)"]}]},{"DOI":"10.13039\/501100002714","name":"University of Freiburg","doi-asserted-by":"publisher","award":["(funding programme Open Access Publishing)"],"award-info":[{"award-number":["(funding programme Open Access Publishing)"]}],"id":[{"id":"10.13039\/501100002714","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>We present a concept for a wafer-level manufactured photoacoustic transducer, suitable to be used in consumer-grade gas sensors. The transducer consists of an anodically bonded two-layer stack of a blank silicon wafer and an 11 \u00b5m membrane, which was wet-etched from a borosilicate wafer. The membrane separates two cavities; one of which was hermetically sealed and filled with CO2 during the anodic bonding and acts as an infrared absorber. The second cavity was designed to be connected to a standard MEMS microphone on PCB-level forming an infrared-sensitive photoacoustic detector. CO2 sensors consisting of the detector and a MEMS infrared emitter were built up and characterized towards their sensitivity and noise levels at six different component distance ranging from 3.0 mm to 15.5 mm. The signal response for the sample with the longest absorption path ranged from a decrease of 8.3% at a CO2 concentration of 9400 ppm to a decrease of 0.8% at a concentration of 560 ppm. A standard deviation of the measured values of 18 ppm was determined when the sensor was exposed to 1000 ppm CO2.<\/jats:p>","DOI":"10.3390\/s22020685","type":"journal-article","created":{"date-parts":[[2022,1,17]],"date-time":"2022-01-17T20:49:21Z","timestamp":1642452561000},"page":"685","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Anodically Bonded Photoacoustic Transducer: An Approach towards Wafer-Level Optical Gas Sensors"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4536-0638","authenticated-orcid":false,"given":"Simon","family":"Gassner","sequence":"first","affiliation":[{"name":"Department of Microsystems Engineering (IMTEK), Albert-Ludwigs-Universit\u00e4t Freiburg, 79085 Freiburg im Breisgau, Germany"},{"name":"Infineon Technologies AG, 81549 Neubiberg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rainer","family":"Schaller","sequence":"additional","affiliation":[{"name":"Infineon Technologies AG, 81549 Neubiberg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Matthias","family":"Eberl","sequence":"additional","affiliation":[{"name":"Infineon Technologies AG, 81549 Neubiberg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carsten","family":"von Koblinski","sequence":"additional","affiliation":[{"name":"Infineon Technologies Austria AG, 9500 Villach, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5874-7719","authenticated-orcid":false,"given":"Simon","family":"Essing","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Technical University of Munich, 80333 M\u00fcnchen, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0546-9732","authenticated-orcid":false,"given":"Mohammadamir","family":"Ghaderi","sequence":"additional","affiliation":[{"name":"Infineon Technologies AG, 81549 Neubiberg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4646-8990","authenticated-orcid":false,"given":"Katrin","family":"Schmitt","sequence":"additional","affiliation":[{"name":"Department of Microsystems Engineering (IMTEK), Albert-Ludwigs-Universit\u00e4t Freiburg, 79085 Freiburg im Breisgau, Germany"},{"name":"Fraunhofer IPM, 79110 Freiburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J\u00fcrgen","family":"W\u00f6llenstein","sequence":"additional","affiliation":[{"name":"Department of Microsystems Engineering (IMTEK), Albert-Ludwigs-Universit\u00e4t Freiburg, 79085 Freiburg im Breisgau, Germany"},{"name":"Fraunhofer IPM, 79110 Freiburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,17]]},"reference":[{"key":"ref_1","unstructured":"Kirby, B.P., Lewis, S.P., and Lewis, P.D. (2021). Do You Think Air? Public interest in Air Pollution. Ergon. Hum. Factors, 8."},{"key":"ref_2","unstructured":"(2021, December 28). Gas Sensor Market Size, Share & Trends Analysis Report By Product (Oxygen\/Lambda Sensor, Carbon Dioxide Sensor), By Type (Wired, Wireless), By Technology, By End Use, By Region, And Segment Forecasts, 2021\u20132028. Available online: https:\/\/www.grandviewresearch.com\/industry-analysis\/gas-sensors-market."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Paleologos, K.E., Selim, M.Y., and Mohamed, A.M.O. (2021). Indoor air quality. Pollution Assessment for Sustainable Practices in Applied Sciences and Engineering, Butterworth-Heinemann.","DOI":"10.1016\/B978-0-12-809582-9.00008-6"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1111\/j.1600-0668.1998.t01-2-00003.x","article-title":"Impact of Temperature and Humidity on the Perception of Indoor Air Quality","volume":"8","author":"Fang","year":"1998","journal-title":"Indoor Air"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"376","DOI":"10.1016\/j.ijheh.2018.01.015","article-title":"Indoor air humidity, air quality, and health\u2014An overview","volume":"221","author":"Wolkoff","year":"2018","journal-title":"Int. J. Hyg. Environ. Health"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1016\/S1001-0742(07)60072-2","article-title":"Evaluation of ambient air quality in Guangzhou, China","volume":"19","author":"Zhou","year":"2007","journal-title":"J. Environ. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1671","DOI":"10.1289\/ehp.1104789","article-title":"Is CO2 an indoor pollutant? Direct effects of low-to-moderate CO2 concentrations on human decision-making performance","volume":"120","author":"Satish","year":"2012","journal-title":"Environ. Health Perspect."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"138047","DOI":"10.1016\/j.scitotenv.2020.138047","article-title":"In-vehicle carbon dioxide and adverse effects: An air filtration-based intervention study","volume":"723","author":"Chen","year":"2020","journal-title":"Sci. Total Environ."},{"key":"ref_9","unstructured":"Von Pettenkofer, M. (1859). \u00dcber den Luftwechsel in Wohngeb\u00e4uden, Cotta\u2019sche Buchhandlung."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"527","DOI":"10.1016\/j.snb.2011.02.024","article-title":"Instability of metal oxide-based conductometric gas sensors and approaches to stability improvement (short survey)","volume":"156","author":"Korotcenkov","year":"2011","journal-title":"Sens. Actuators B Chem."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Tille, T. (2016). Chemoresistive CO2-Sensoren basierend auf Seltenerdoxycarbonat-beladenem Zinndioxid. Automobil-Sensorik, Springer.","DOI":"10.1007\/978-3-662-48944-4"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Ersoez, B., Bauersfeld, M.L., and W\u00f6llenstein, J. (2017). Ionogel\u2014Based Composite Material for CO2 Sensing Deposited on a Chemiresistive Transducer. Proceedings, 1.","DOI":"10.3390\/proceedings1040314"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"128201","DOI":"10.1016\/j.snb.2020.128201","article-title":"Electrolyte-gated transistor for CO2 gas detection at room temperature","volume":"317","author":"Schmitt","year":"2020","journal-title":"Sens. Actuators B Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/0925-4005(94)01584-5","article-title":"Detection of CO2 using a qaurtz crystal microbalance","volume":"26","author":"Gomes","year":"1995","journal-title":"Sens. Actuators B Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1002\/ecj.11601","article-title":"A CO2 Sensor Using a Quartz Crystal Microbalance Coated with a Sensitive Membrane","volume":"97","author":"Muraoka","year":"2014","journal-title":"Electron. Commun. Jpn."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"580","DOI":"10.1016\/j.snb.2013.06.006","article-title":"Non-dispersive infra-red (NDIR) measurement of carbon dioxide at 4.2 \u03bcm in a compact and optically efficient sensor","volume":"186","author":"Hodgkinson","year":"2013","journal-title":"Sens. Actuators B Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"510","DOI":"10.1080\/14786448108627053","article-title":"LXVIII. Upon the production of sound by radiant energy","volume":"11","author":"Bell","year":"1881","journal-title":"Lond. Edinb. Dublin Philos. Mag. J. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1080\/14786448108627021","article-title":"On tones produced by the intermittent irradiation of a gas","volume":"11","year":"1881","journal-title":"Lond. Edinb. Dublin Philos. Mag. J. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1524\/teme.2013.0052","article-title":"Kompaktes photoakustisches Gasmesssystem mit Potential zur weiteren Miniaturisierung","volume":"80","author":"Huber","year":"2013","journal-title":"tm-Tech. Mess."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Gerlach, G. (2019). Photoacoustic Detection of CO2: 8. Carbon Dioxide Sensing, Wiley-VCH Verlag GmbH & Co. KGaA.","DOI":"10.1002\/9783527688302"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1063\/1.1740948","article-title":"Theoretical consideration in heat and infra-red detection, with particular reference to the pneumatic detector","volume":"18","author":"Golay","year":"1947","journal-title":"Rev. Sci. Instrum."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"34","DOI":"10.2307\/2310304","article-title":"An Algorithm for the Evaluation of Finite Trigonometric Series","volume":"65","author":"Goertzel","year":"1958","journal-title":"Am. Math. Mon."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.jqsrt.2016.03.005","article-title":"HITRAN Application Programming Interface (HAPI): A comprehensive approach to working with spectroscopic data","volume":"177","author":"Kochanov","year":"2016","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"107949","DOI":"10.1016\/j.jqsrt.2021.107949","article-title":"The HITRAN2020 molecular spectroscopic database","volume":"277","author":"Gordon","year":"2022","journal-title":"J. Quant. Spectrosc. Radiat. Transf."},{"key":"ref_25","unstructured":"Eberl, M., Jost, F., Kolb, S., Schaller, R., Dettmann, D., Gassner, S., and Skorupa, F. (2019). Miniaturized photoacoustic CO2 gas sensors\u2014A new approach for the automotive sector. AmE 2019\u2014Automotive Meets Electronics, Proceedings of the 10th GMM-Symposium, Dortmund, Germany, 12\u201313 March 2019, VDE Verlag."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/j.proeng.2016.11.111","article-title":"Photoacoustic CO2-Sensor for Automotive Applications","volume":"168","author":"Huber","year":"2016","journal-title":"Procedia Eng."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Tille, T. (2016). Photoakustischer Low-Cost CO2-Sensor f\u00fcr Automobilanwendungen. Automobil-Sensorik, Springer.","DOI":"10.1007\/978-3-662-48944-4"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Weber, C., El-Safoury, M., Eberhardt, A., Schmitt, K., and W\u00f6llenstein, J. (2019). 4.2.2 Miniaturisiere Photoakustische Detektoren f\u00fcr den Nachweis Fluorhaltiger K\u00e4ltemittel, AMA Service GmbH. Tagungsband.","DOI":"10.5162\/sensoren2019\/4.2.2"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"207","DOI":"10.1016\/j.sna.2006.02.019","article-title":"High-resolution pressure sensor for photo acoustic gas detection","volume":"132","author":"Wang","year":"2006","journal-title":"Sens. Actuators A Phys."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"930","DOI":"10.1016\/j.snb.2017.03.086","article-title":"Design of a LED-based sensor for monitoring the lower explosion limit of methane","volume":"247","author":"Wittstock","year":"2017","journal-title":"Sens. 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