{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T20:06:05Z","timestamp":1777493165779,"version":"3.51.4"},"reference-count":47,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2018,3,12]],"date-time":"2018-03-12T00:00:00Z","timestamp":1520812800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The development of portable low-cost integrated optics-based biosensors for photonics-on-a-chip devices for real-time diagnosis are of great interest, offering significant advantages over current analytical methods. We report the fabrication and characterization of an optical sensor based on a Mach-Zehnder interferometer to monitor the growing concentration of bacteria in a liquid medium. The device pattern was imprinted on transparent self-patternable organic-inorganic di-ureasil hybrid films by direct UV-laser, reducing the complexity and cost production compared with lithographic techniques or three-dimensional (3D) patterning using femtosecond lasers. The sensor performance was evaluated using, as an illustrative example, E. coli cell growth in an aqueous medium. The measured sensitivity (2 \u00d7 10\u22124 RIU) and limit of detection (LOD = 2 \u00d7 10\u22124) are among the best values known for low-refractive index contrast sensors. Furthermore, the di-ureasil hybrid used to produce this biosensor has additional advantages, such as mechanical flexibility, thermal stability, and low insertion losses due to fiber-device refractive index mismatch (~1.49). Therefore, the proposed sensor constitutes a direct, compact, fast, and cost-effective solution for monitoring the concentration of lived-cells.<\/jats:p>","DOI":"10.3390\/s18030840","type":"journal-article","created":{"date-parts":[[2018,3,12]],"date-time":"2018-03-12T13:13:48Z","timestamp":1520860428000},"page":"840","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":30,"title":["Integrated Optical Mach-Zehnder Interferometer Based on Organic-Inorganic Hybrids for Photonics-on-a-Chip Biosensing Applications"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3251-6306","authenticated-orcid":false,"given":"Ana","family":"Bastos","sequence":"first","affiliation":[{"name":"Department of Physics and CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810\u2013193 Aveiro, Portugal"},{"name":"Instituto de Telecomunica\u00e7\u00f5es, University of Aveiro, 3810\u2013193 Aveiro, Portugal"},{"name":"Department of Electronics, Telecommunications and Informatics, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0701-1901","authenticated-orcid":false,"given":"Carlos","family":"Vicente","sequence":"additional","affiliation":[{"name":"Department of Physics and CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810\u2013193 Aveiro, Portugal"},{"name":"Instituto de Telecomunica\u00e7\u00f5es, University of Aveiro, 3810\u2013193 Aveiro, Portugal"}]},{"given":"Rui","family":"Oliveira-Silva","sequence":"additional","affiliation":[{"name":"Department of Physics and CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810\u2013193 Aveiro, Portugal"}]},{"given":"Nuno","family":"Silva","sequence":"additional","affiliation":[{"name":"Department of Physics and CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810\u2013193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7965-4928","authenticated-orcid":false,"given":"Marta","family":"Tac\u00e3o","sequence":"additional","affiliation":[{"name":"Department of Biology and CESAM, University of Aveiro, 3810\u2013193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1871-7160","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Costa","sequence":"additional","affiliation":[{"name":"Department of Chemistry and CESAM, University of Aveiro, 3810\u2013193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4925-3781","authenticated-orcid":false,"given":"M\u00e1rio","family":"Lima","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, University of Aveiro, 3810\u2013193 Aveiro, Portugal"},{"name":"Department of Electronics, Telecommunications and Informatics, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"given":"Paulo","family":"Andr\u00e9","sequence":"additional","affiliation":[{"name":"Department of Electric and Computer Engineering and Instituto de Telecomunica\u00e7\u00f5es, Instituto Superior T\u00e9cnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal"}]},{"given":"Rute","family":"Ferreira","sequence":"additional","affiliation":[{"name":"Department of Physics and CICECO\u2014Aveiro Institute of Materials, University of Aveiro, 3810\u2013193 Aveiro, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2018,3,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"11","DOI":"10.3389\/fbioe.2016.00011","article-title":"Recent Advances in Biosensor Technology for Potential Applications\u2014An Overview","volume":"4","author":"Vigneshvar","year":"2016","journal-title":"Front. 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