{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T11:10:52Z","timestamp":1789125052520,"version":"build-2803163510"},"reference-count":29,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T00:00:00Z","timestamp":1789084800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Safran Tech","award":["24S009"],"award-info":[{"award-number":["24S009"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>To enable fiber Bragg gratings (FBGs) to operate effectively as cryogenic temperature sensors, metals with high thermal expansion coefficients should be deposited onto the surface of an optical fiber. In this work, targeting aerospace applications, a copper\u2013indium bimetallic-coated FBG designed for operation at around 850 nm was manufactured using sputtering and electrodeposition techniques. Furthermore, the influence of bonding materials, specifically Kapton tape and Apiezon N grease, as well as fixation methods, on the performance of the coated FBG was investigated during cryogenic temperature calibration. The results demonstrate that with Kapton tape bonding, the Bragg wavelength shift (BWS) was approximately 1.6 times greater than that obtained with Apiezon N grease at 77 K during sensor calibrations. However, in order to have efficient thermal coupling between the sample holder and the metal-coated sensor in harsh environments such as cryogenic and vacuum environments, the optimal choice of bonding material as well as its architecture is mandatory to achieve high sensor sensitivity. Therefore, this study gives insights into the fact that metal-coated FBGs\u2019 calibration accuracy and real-time stability during sensor deployments can be affected by the fixing techniques and the bonding materials used.<\/jats:p>","DOI":"10.3390\/s26185773","type":"journal-article","created":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T10:51:37Z","timestamp":1789123897000},"page":"5773","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effect of Bonding Material and Fixing Techniques on the Calibration of Copper\u2013Indium Bimetallic-Coated FBG-Based Cryogenic Temperature Sensors for Aerospace Applications"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5385-9538","authenticated-orcid":false,"given":"Abrham Kassa","family":"Alem","sequence":"first","affiliation":[{"name":"Laboratoire Hubert Curien, UMR CNRS 5516, Universit\u00e9 Jean Monnet, 42000 Saint-Etienne, 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