{"type": "FeatureCollection", "features": [{"id": "10.1117/12.2624501", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-22T16:18:07Z", "type": "Journal Article", "created": "2022-05-19", "title": "Pre-strain effects on CYTOP fibre Bragg grating temperature sensors", "description": "Cyclic transparent optical polymer (CYTOP) based fibre Bragg grating (FBG) sensors are of high interest recently due to their lower optical loss compared with the sensors fabricated in other polymeric materials, such as poly(methyl methacrylate). Numerous scientific reports have shown that polymer based FBGs are usually preferred over their silica counterparts due to their enhanced sensitivity to stress and pressure, and their affinity to humidity. Temperature monitoring with polymer FBGs is also extensively demonstrated, but with inconsistent results and non-linear responses, since most of the polymer optical fibres have a negative thermo-optic coefficient and positive thermal expansion coefficient that work to cancel out each other to some extent, resulting in mixed temperature sensitivities. In this work, an optical fibre with a CYTOP core and a Xylex cladding is used to investigate fibre pre-strain effects on the temperature sensitivity of FBG sensors. The sensors were placed in an environmental chamber with controlled temperature and relative humidity, and their response to temperature was evaluated under various fibre pre-strain values. Without any applied fibre strain, the thermal expansion coefficient slightly prevails over the thermo-optic effect, as a result the Bragg wavelength shifts in longer wavelengths. Under sufficient fibre strain, the thermal expansion coefficient is eliminated, and the temperature sensitivity is greatly enhanced, shifting the Bragg wavelength to shorter wavelengths. This paper demonstrates the possibility to have an array of Bragg grating sensors, some being temperature insensitive and some highly temperature sensitive along the same fibre.", "keywords": ["polymer optical fibre", "optical polymer", "fibre Bragg grating sensors", "0103 physical sciences", "Bragg gratings", "Engineering and Technology", "Electrical Engineering - Electronic Engineering - Information Engineering", "01 natural sciences", "temperature sensing"], "contacts": [{"organization": "Pospori, Andreas, Ioannou, Andreas, Kalli, Kyriacos,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1117/12.2624501"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Micro-Structured%20and%20Specialty%20Optical%20Fibres%20VII", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1117/12.2624501", "name": "item", "description": "10.1117/12.2624501", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1117/12.2624501"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-05-19T00:00:00Z"}}, {"id": "10.3390/s22197233", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-22T16:19:29Z", "type": "Journal Article", "created": "2022-09-26", "title": "Temperature and Humidity Sensitivity of Polymer Optical Fibre Sensors Tuned by Pre-Strain", "description": "<p>Polymer optical fibre Bragg grating (POFBG) sensors are of high interest due to their enhanced fracture toughness, flexibility in bending, and sensitivity in stress and pressure monitoring applications compared to silica-based sensors. The POFBG sensors can also detect humidity due to the hydrophilic nature of some polymers. However, multi-parameter sensing can cause cross-sensitivity issues in certain applications if the temperature and humidity measurements are not adequately compensated. In this work, we demonstrate the possibility of selectively tuning sensors\uffe2\uff80\uff99 temperature and humidity sensitivities to the desired level by applying a certain amount of fibre pre-strain. The temperature sensitivity of POFBG sensors fabricated in perfluoropolymers (CYTOP) can be selectively tuned from positive to negative values, having the option for insensitivity in specific temperature ranges depending on the amount of the applied pre-strain. The humidity sensitivity of sensors can also be changed from positive values to insensitivity. The importance of thermal annealing treatment of POFBG sensors for improved repeatability in temperature measurements is also reported. An array of 4 multiplexed POFBGs was fabricated, and each sensor was pre-strained accordingly to demonstrate the possibility of having targeted temperature and humidity sensitivities along the same fibre.</p>", "keywords": ["Chemical technology", "humidity", "temperature", "fibre Bragg gratings", "TP1-1185", "Electrical Engineering - Electronic Engineering - Information Engineering", "sensors", "sensitivity", "01 natural sciences", "Article", "polymer optical fibre", "0103 physical sciences", "Engineering and Technology", "XYLEX", "polymer optical fibre; fibre Bragg gratings; sensors; temperature; humidity; sensitivity; CYTOP; XYLEX", "CYTOP"]}, "links": [{"href": "http://www.mdpi.com/1424-8220/22/19/7233/pdf"}, {"href": "https://www.mdpi.com/1424-8220/22/19/7233/pdf"}, {"href": "https://doi.org/10.3390/s22197233"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Sensors", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.3390/s22197233", "name": "item", "description": "10.3390/s22197233", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.3390/s22197233"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-09-23T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=polymer+optical+fibre&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=polymer+optical+fibre&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=polymer+optical+fibre&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=polymer+optical+fibre&offset=2", "hreflang": "en-US"}], "numberMatched": 2, "numberReturned": 2, "distributedFeatures": [], "timeStamp": "2026-09-22T22:52:37.578959Z"}