{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,30]],"date-time":"2026-04-30T06:32:20Z","timestamp":1777530740257,"version":"3.51.4"},"reference-count":24,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2020,10,24]],"date-time":"2020-10-24T00:00:00Z","timestamp":1603497600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008530","name":"European Regional Development Fund","doi-asserted-by":"publisher","award":["85003655 and 85003502"],"award-info":[{"award-number":["85003655 and 85003502"]}],"id":[{"id":"10.13039\/501100008530","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["EXC 2122, Project ID 390833453"],"award-info":[{"award-number":["EXC 2122, Project ID 390833453"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Lower Saxony","award":["\u201cQuanten- und Nanometrologie\u201d (QUANOMET)"],"award-info":[{"award-number":["\u201cQuanten- und Nanometrologie\u201d (QUANOMET)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In recent years, lanthanide-doped nanothermometers have been mainly used in thin films or dispersed in organic solvents. However, both approaches have disadvantages such as the short interaction lengths of the active material with the pump beam or complicated handling, which can directly affect the achievable temperature resolution. We investigated the usability of a polymer fiber doped with upconversion nanocrystals as a thermometer. The fiber was excited with a wavelength stabilized diode laser at a wavelength of 976 nm. Emission spectra were recorded in a temperature range from 10 to 35 \u2218C and the thermal emission changes were measured. Additionally, the pump power was varied to study the effect of self-induced heating on the thermometer specifications. Our fiber sensor shows a maximal thermal sensitivity of 1.45%\/K and the minimal thermal resolution is below 20 mK. These results demonstrate that polymer fibers doped with nanocrystals constitute an attractive alternative to conventional fluorescence thermometers, as they add a long pump interaction length while also being insensitive to strong electrical fields or inert to bio-chemical environments.<\/jats:p>","DOI":"10.3390\/s20216048","type":"journal-article","created":{"date-parts":[[2020,10,26]],"date-time":"2020-10-26T03:51:47Z","timestamp":1603684307000},"page":"6048","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Upconversion Nanocrystal Doped Polymer Fiber Thermometer"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5437-1216","authenticated-orcid":false,"given":"Jonas","family":"Thiem","sequence":"first","affiliation":[{"name":"Institut of Quantum Optics, Leibniz University Hannover, Welfengarten 1, D-30167 Hannover, Germany"},{"name":"Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1387-0577","authenticated-orcid":false,"given":"Simon","family":"Spelthann","sequence":"additional","affiliation":[{"name":"Institut of Quantum Optics, Leibniz University Hannover, Welfengarten 1, D-30167 Hannover, Germany"},{"name":"Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laurie","family":"Neumann","sequence":"additional","affiliation":[{"name":"TU Braunschweig, Institut f\u00fcr Hochfrequenztechnik, Schleinitzsta\u00dfe 22, D-38106 Braunschweig, Germany"},{"name":"Academic Alliance Braunschweig-Hannover QUANOMET, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5166-0813","authenticated-orcid":false,"given":"Florian","family":"Jakobs","sequence":"additional","affiliation":[{"name":"TU Braunschweig, Institut f\u00fcr Hochfrequenztechnik, Schleinitzsta\u00dfe 22, D-38106 Braunschweig, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hans-Hermann","family":"Johannes","sequence":"additional","affiliation":[{"name":"TU Braunschweig, Institut f\u00fcr Hochfrequenztechnik, Schleinitzsta\u00dfe 22, D-38106 Braunschweig, Germany"},{"name":"Academic Alliance Braunschweig-Hannover QUANOMET, 30167 Hannover, Germany"},{"name":"Cluster of Excellence PhoenixD, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wolfgang","family":"Kowalsky","sequence":"additional","affiliation":[{"name":"TU Braunschweig, Institut f\u00fcr Hochfrequenztechnik, Schleinitzsta\u00dfe 22, D-38106 Braunschweig, Germany"},{"name":"Academic Alliance Braunschweig-Hannover QUANOMET, 30167 Hannover, Germany"},{"name":"Cluster of Excellence PhoenixD, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dietmar","family":"Kracht","sequence":"additional","affiliation":[{"name":"Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany"},{"name":"Cluster of Excellence PhoenixD, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joerg","family":"Neumann","sequence":"additional","affiliation":[{"name":"Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany"},{"name":"Cluster of Excellence PhoenixD, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Axel","family":"Ruehl","sequence":"additional","affiliation":[{"name":"Institut of Quantum Optics, Leibniz University Hannover, Welfengarten 1, D-30167 Hannover, Germany"},{"name":"Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany"},{"name":"Academic Alliance Braunschweig-Hannover QUANOMET, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Detlev","family":"Ristau","sequence":"additional","affiliation":[{"name":"Institut of Quantum Optics, Leibniz University Hannover, Welfengarten 1, D-30167 Hannover, Germany"},{"name":"Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany"},{"name":"Academic Alliance Braunschweig-Hannover QUANOMET, 30167 Hannover, Germany"},{"name":"Cluster of Excellence PhoenixD, 30167 Hannover, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,10,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1186\/1475-925X-1-2","article-title":"Temperature measurement on neurological pulse generators during MR scans","volume":"1","author":"Kainz","year":"2002","journal-title":"Biomed. 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