{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,19]],"date-time":"2026-03-19T13:06:30Z","timestamp":1773925590402,"version":"3.50.1"},"reference-count":33,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2019,9,30]],"date-time":"2019-09-30T00:00:00Z","timestamp":1569801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100012331","name":"Agentschap Innoveren en Ondernemen","doi-asserted-by":"publisher","award":["160580"],"award-info":[{"award-number":["160580"]}],"id":[{"id":"10.13039\/100012331","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, we propose a novel, miniaturized non-dispersive infrared (NDIR) CO2 sensor implemented on a silicon chip. The sensor has a simple structure, consisting of a hollow metallic cylindrical cavity along with access waveguides. A detailed analysis of the proposed sensor is presented. Simulation with 3D ray tracing shows that an integrating cylinder with 4 mm diameter gives an equivalent optical path length of 3.5 cm. The sensor is fabricated using Deep Reactive Ion Etching (DRIE) and wafer bonding. The fabricated sensor was evaluated by performing a CO2 concentration measurement, showing a limit of detection of \u223c100 ppm. The response time of the sensor is only \u223c2.8 s, due to its small footprint. The use of DRIE-based waveguide structures enables mass fabrication, as well as the potential co-integration of flip-chip integrated midIR light-emitting diodes (LEDs) and photodetectors, resulting in a compact, low-power, and low-cost NDIR CO2 sensor.<\/jats:p>","DOI":"10.3390\/s19194260","type":"journal-article","created":{"date-parts":[[2019,9,30]],"date-time":"2019-09-30T13:16:41Z","timestamp":1569849401000},"page":"4260","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":39,"title":["On-Chip Non-Dispersive Infrared CO2 Sensor Based on an Integrating Cylinder \u2020"],"prefix":"10.3390","volume":"19","author":[{"given":"Xiaoning","family":"Jia","sequence":"first","affiliation":[{"name":"Photonics Research Group, INTEC, Ghent University-imec, Technologiepark 126, 9052 Gent, Belgium"},{"name":"Center for Nano- and Biophotonics, Ghent University, 9000 Gent, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joris","family":"Roels","sequence":"additional","affiliation":[{"name":"Melexis Technologies NV, Transportstraat 1, 3980 Tessenderlo, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Roel","family":"Baets","sequence":"additional","affiliation":[{"name":"Photonics Research Group, INTEC, Ghent University-imec, Technologiepark 126, 9052 Gent, Belgium"},{"name":"Center for Nano- and Biophotonics, Ghent University, 9000 Gent, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4667-5092","authenticated-orcid":false,"given":"Gunther","family":"Roelkens","sequence":"additional","affiliation":[{"name":"Photonics Research Group, INTEC, Ghent University-imec, Technologiepark 126, 9052 Gent, Belgium"},{"name":"Center for Nano- and Biophotonics, Ghent University, 9000 Gent, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,9,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Ortiz Perez, A., Bierer, B., Scholz, L., W\u00f6llenstein, J., and Palzer, S. 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