{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,18]],"date-time":"2026-01-18T12:26:36Z","timestamp":1768739196947,"version":"3.49.0"},"reference-count":29,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2020,3,30]],"date-time":"2020-03-30T00:00:00Z","timestamp":1585526400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000265","name":"Medical Research Council","doi-asserted-by":"publisher","award":["MR\/R025266\/1"],"award-info":[{"award-number":["MR\/R025266\/1"]}],"id":[{"id":"10.13039\/501100000265","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>An optical fibre sensor for monitoring relative humidity (RH) changes during exercise is demonstrated. The humidity sensor comprises a tip coating of poly (allylamine hydrochloride) (PAH)\/silica nanoparticles (SiO2 NPs) deposited using the layer-by-layer technique. An uncoated fibre is employed to compensate for bending losses that are likely to occur during movement. A linear fit to the response of the sensing system to RH demonstrates a sensitivity of 3.02 mV\/% (R2 = 0.96), hysteresis \u00b1 1.17% RH when 11 bilayers of PAH\/SiO2 NPs are coated on the tip of the fibre. The performance of two different textiles (100% cotton and 100% polyester) were tested in real-time relative humidity measurement for 10 healthy volunteers. The results demonstrate the moisture wicking properties of polyester in that the relative humidity dropped more rapidly after cessation of exercise compared to cotton. The approach has the potential to be used to monitor sports performance and by clothing developers for characterising different garment designs.<\/jats:p>","DOI":"10.3390\/s20071904","type":"journal-article","created":{"date-parts":[[2020,4,1]],"date-time":"2020-04-01T03:44:13Z","timestamp":1585712653000},"page":"1904","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Real-Time Humidity Measurement during Sports Activity using Optical Fibre Sensing"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4679-3160","authenticated-orcid":false,"given":"Chenyang","family":"He","sequence":"first","affiliation":[{"name":"Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5179-6991","authenticated-orcid":false,"given":"Serhiy","family":"Korposh","sequence":"additional","affiliation":[{"name":"Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francisco Ulises","family":"Hernandez","sequence":"additional","affiliation":[{"name":"Footfalls and Heartbeats UK Ltd, Innovation Building, Biocity, Nottingham NG1 1GF, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0958-069X","authenticated-orcid":false,"given":"Liangliang","family":"Liu","sequence":"additional","affiliation":[{"name":"Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ricardo","family":"Correia","sequence":"additional","affiliation":[{"name":"Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4237-7001","authenticated-orcid":false,"given":"Barrie R.","family":"Hayes-Gill","sequence":"additional","affiliation":[{"name":"Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4069-3801","authenticated-orcid":false,"given":"Stephen P.","family":"Morgan","sequence":"additional","affiliation":[{"name":"Optics and Photonics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK"},{"name":"Footfalls and Heartbeats UK Ltd, Innovation Building, Biocity, Nottingham NG1 1GF, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,3,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4034","DOI":"10.1016\/j.buildenv.2006.06.037","article-title":"Effect of humidity on human comfort and productivity after step changes from warm and humid environment","volume":"42","author":"Tsutsumi","year":"2007","journal-title":"Build. Environ."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2313","DOI":"10.1007\/s00421-011-2206-7","article-title":"Influence of relative humidity on prolonged exercise capacity in a warm environment","volume":"112","author":"Maughan","year":"2012","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"347","DOI":"10.47102\/annals-acadmedsg.V37N4p347","article-title":"Human thermoregulation and measurement of body temperature in exercise and clinical settings","volume":"37","author":"Lim","year":"2008","journal-title":"Ann. Acad. Med. Singap."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"598","DOI":"10.1177\/1420326X12447614","article-title":"Impact of relative humidity on thermal comfort in a warm environment","volume":"22","author":"Jing","year":"2013","journal-title":"Indoor Built Environ."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"138","DOI":"10.1016\/j.apergo.2014.11.012","article-title":"Novel ventilation design of combining spacer and mesh structure in sports T-shirt significantly improves thermal comfort","volume":"48","author":"Sun","year":"2015","journal-title":"Appl. Ergon."},{"key":"ref_6","first-page":"51","article-title":"Possibility of Modern Humidity Sensor Application in the Studies of Moisture Transport through the Sports and Outdoor Garments","volume":"978","author":"Koptyug","year":"2016","journal-title":"icSPORTS"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"2155","DOI":"10.1007\/s00421-018-3941-9","article-title":"Spatial and temporal migration of sweat: From skin to clothing","volume":"118","author":"Raccuglia","year":"2018","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e51","DOI":"10.1016\/j.scispo.2017.03.009","article-title":"A wearable sweat rate sensor to monitor the athletes\u2019 performance during training","volume":"33","author":"Salvo","year":"2018","journal-title":"Sci. Sport"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"073003","DOI":"10.1088\/2040-8986\/aac68d","article-title":"Biomedical application of optical fibre sensors","volume":"20","author":"Correia","year":"2018","journal-title":"J. Opt."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Ascorbe, J., Corres, J., Arregui, F., and Matias, I. (2017). Recent Developments in Fiber Optics Humidity Sensors. Sensors, 17.","DOI":"10.3390\/s17040893"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1065","DOI":"10.1016\/j.snb.2016.09.144","article-title":"Photonic crystal fiber interferometer coated with a PAH\/PAA nanolayer as humidity sensor","volume":"242","author":"Elosua","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1059","DOI":"10.1016\/j.snb.2017.05.125","article-title":"Enhancing sensitivity of photonic crystal fiber interferometric humidity sensor by the thickness of SnO2 thin films","volume":"251","author":"Elosua","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"031107","DOI":"10.1063\/1.4959092","article-title":"Fiber optic relative humidity sensor based on the tilted fiber Bragg grating coated with graphene oxide","volume":"109","author":"Wang","year":"2016","journal-title":"Appl. Phys. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"4140","DOI":"10.1364\/OE.19.004140","article-title":"Optical fiber relative humidity sensor based on FBG incorporated thin-core fiber modal interferometer","volume":"19","author":"Gu","year":"2011","journal-title":"Opt. Express"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"880","DOI":"10.1109\/LPT.2007.897551","article-title":"Long-period grating relative humidity sensor with hydrogel coating","volume":"19","author":"Liu","year":"2007","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2615","DOI":"10.1109\/JSEN.2014.2312353","article-title":"Highly sensitive carbon nanotubes coated etched fiber bragg grating sensor for humidity sensing","volume":"14","author":"Shivananju","year":"2014","journal-title":"IEEE Sens. J."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1016\/j.snb.2012.07.032","article-title":"Polyvinyl alcohol coated photonic crystal optical fiber sensor for humidity measurement","volume":"174","author":"Wong","year":"2012","journal-title":"Sens. Actuators B Chem."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"5310","DOI":"10.1364\/AO.50.005310","article-title":"Zinc oxide nanoparticle based optical fiber humidity sensor having linear response throughout a large dynamic range","volume":"50","author":"Aneesh","year":"2011","journal-title":"Appl. Opt."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1985","DOI":"10.1109\/TBME.2016.2521662","article-title":"Characterization and Use of a Fiber Optic Sensor Based on PAH\/SiO2 Film for Humidity Sensing in Ventilator Care Equipment","volume":"63","author":"Hernandez","year":"2016","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"887","DOI":"10.1016\/j.snb.2017.07.191","article-title":"Polymeric optical fibre sensor coated by SiO2 nanoparticles for humidity sensing in the skin microenvironment","volume":"254","author":"Gomez","year":"2018","journal-title":"Sens. Actuators B Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/S0925-4005(00)00524-4","article-title":"Optical fiber humidity sensor based on a tapered fiber coated with agarose gel","volume":"69","author":"Arregui","year":"2000","journal-title":"Sens. Actuators B Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2133","DOI":"10.1002\/mop.22671","article-title":"Investigation of macrobending losses of standard single mode fiber with small bend radii","volume":"49","author":"Wang","year":"2007","journal-title":"Microw. Opt. Technol. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"300","DOI":"10.1016\/j.snb.2012.07.005","article-title":"Pronounced aromatic carboxylic acid detection using a layer-by-layer mesoporous coating on optical fibre long period grating","volume":"173","author":"Korposh","year":"2012","journal-title":"Sens. Actuators B Chem."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"216","DOI":"10.1364\/JOSA.66.000216","article-title":"Curvature loss formula for optical fibers","volume":"66","author":"Marcuse","year":"2008","journal-title":"J. Opt. Soc. Am."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1364\/OL.24.000596","article-title":"Optical fiber nanometer-scale Fabry\u2013Perot interferometer formed by the ionic self-assembly monolayer process","volume":"24","author":"Arregui","year":"2008","journal-title":"Opt. Lett."},{"key":"ref_26","first-page":"335","article-title":"Lessons in biostatistics","volume":"25","author":"Breslow","year":"2014","journal-title":"Past Present. Futur. Stat. Sci."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1177\/004051759506500507","article-title":"Fiber Hygroscopicity and Perceptions of Dampness","volume":"65","author":"Plante","year":"1995","journal-title":"Text. Res. J."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"6611","DOI":"10.1128\/AEM.01422-14","article-title":"Microbial Odor Profile of Polyester and Cotton Clothes after a Fitness Session","volume":"80","author":"Callewaert","year":"2014","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"5646","DOI":"10.1364\/OL.40.005646","article-title":"Miniature all-silica fiber-optic sensor for simultaneous measurement of relative humidity and temperature","volume":"40","author":"Pevec","year":"2015","journal-title":"Opt. Lett."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/7\/1904\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:13:13Z","timestamp":1760173993000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/7\/1904"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,3,30]]},"references-count":29,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2020,4]]}},"alternative-id":["s20071904"],"URL":"https:\/\/doi.org\/10.3390\/s20071904","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,3,30]]}}}