{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,13]],"date-time":"2026-05-13T17:25:24Z","timestamp":1778693124602,"version":"3.51.4"},"reference-count":42,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2024,2,7]],"date-time":"2024-02-07T00:00:00Z","timestamp":1707264000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003246","name":"the Netherlands Organisation for Scientific Research (NWO) \u201cSynergia-SYstem change for New Ecology-based and Resource efficient Growth with high tech In Agriculture\u201d","doi-asserted-by":"publisher","award":["17626"],"award-info":[{"award-number":["17626"]}],"id":[{"id":"10.13039\/501100003246","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The presence of an elevated amount of methane (CH4) in exhaled breath can be used as a non-invasive tool to monitor certain health conditions. A compact, inexpensive and transportable CH4 sensor is thus very interesting for this purpose. In addition, if the sensor is also able to simultaneously measure carbon dioxide (CO2), one can extract the end-tidal concentration of exhaled CH4. Here, we report on such a sensor based on a commercial detection module using tunable diode laser absorption spectroscopy. It was found that the measured CH4\/CO2 values exhibit a strong interference with water vapor. Therefore, correction functions were experimentally identified and validated for both CO2 and CH4. A custom-built breath sampler was developed and tested with the sensor for real-time measurements of CH4 and CO2 in exhaled breath. As a result, the breath sensor demonstrated the capability of accurately measuring the exhaled CH4 and CO2 profiles in real-time. We obtained minimum detection limits of ~80 ppbv for CH4 and ~700 ppmv for CO2 in 1.5 s measurement time.<\/jats:p>","DOI":"10.3390\/s24041077","type":"journal-article","created":{"date-parts":[[2024,2,7]],"date-time":"2024-02-07T03:47:09Z","timestamp":1707277629000},"page":"1077","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Real-Time Measurement of CH4 in Human Breath Using a Compact CH4\/CO2 Sensor"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9139-7506","authenticated-orcid":false,"given":"Yueyu","family":"Lin","sequence":"first","affiliation":[{"name":"Life Science Trace Detection Laboratory, Department of Analytical Chemistry and Chemometrics, Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6968-5779","authenticated-orcid":false,"given":"Dexter","family":"Manalili","sequence":"additional","affiliation":[{"name":"Life Science Trace Detection Laboratory, Department of Analytical Chemistry and Chemometrics, Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amir","family":"Khodabakhsh","sequence":"additional","affiliation":[{"name":"Life Science Trace Detection Laboratory, Department of Analytical Chemistry and Chemometrics, Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9012-4119","authenticated-orcid":false,"given":"Simona M.","family":"Cristescu","sequence":"additional","affiliation":[{"name":"Life Science Trace Detection Laboratory, Department of Analytical Chemistry and Chemometrics, Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,2,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"235","DOI":"10.1080\/19490976.2016.1182288","article-title":"H2 Metabolism Is Widespread and Diverse among Human Colonic Microbes","volume":"7","author":"Wolf","year":"2016","journal-title":"Gut Microbes"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1097\/MCO.0b013e3283619e63","article-title":"Carbohydrates and the Human Gut Microbiota","volume":"16","author":"Chassard","year":"2013","journal-title":"Curr. 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