{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,12]],"date-time":"2026-02-12T11:19:55Z","timestamp":1770895195890,"version":"3.50.1"},"reference-count":29,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2019,5,30]],"date-time":"2019-05-30T00:00:00Z","timestamp":1559174400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"This work is funded by FCT\/MEC through national funds and when applicable co-funded by FEDER \u2013 PT2020 partnership agreement under the project INITIATE","award":["IF\/01664\/2014\/CP1257\/CT0002"],"award-info":[{"award-number":["IF\/01664\/2014\/CP1257\/CT0002"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this study the influence of the surface roughness on the transmission capacities of D-shaped plastic optical fibers (POFs) and sensors performance was investigated. Five D-shaped POF sensors were produced and characterized for refractive index sensing between 1.33 and 1.41. The sensors were characterized using a low-cost optical sensing system based on the variation of the transmitted light though the POF with refractive index changes (RI). Higher surface roughness increases the scattering losses through the POF and influences the sensors\u2019 performance; therefore, a balance must be attained. Generally, the best performance was achieved when the sensing region was polished with P600 sandpaper as a final polishing step. Polishing with sandpapers of lower grit size resulted in lower scattering, higher linearity of the sensor response and generally lower performance for RI sensing. A sensor resolution of 10\u22123\u201310\u22124 RIU, dependent on the value of the external refractive index, was obtained through simple and low-cost manufacturing procedures. The obtained results show the importance of surface roughness in the development of POF sensors which can be used in several applications, such as for water quality assessment.<\/jats:p>","DOI":"10.3390\/s19112476","type":"journal-article","created":{"date-parts":[[2019,5,30]],"date-time":"2019-05-30T11:07:44Z","timestamp":1559214464000},"page":"2476","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":39,"title":["D-Shaped POF Sensors for Refractive Index Sensing\u2014The Importance of Surface Roughness"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6681-1282","authenticated-orcid":false,"given":"Filipa","family":"Sequeira","sequence":"first","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, 3810-193 Aveiro, Portugal"},{"name":"Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"CESAM, University of Aveiro, 3810-193 Aveiro, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7769-0984","authenticated-orcid":false,"given":"Nunzio","family":"Cennamo","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Campania Luigi Vanvitelli, 81031 Aversa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alisa","family":"Rudnitskaya","sequence":"additional","affiliation":[{"name":"CESAM, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rog\u00e9rio","family":"Nogueira","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, 3810-193 Aveiro, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luigi","family":"Zeni","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Campania Luigi Vanvitelli, 81031 Aversa, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8804-593X","authenticated-orcid":false,"given":"L\u00facia","family":"Bilro","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, 3810-193 Aveiro, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.ecoenv.2017.07.027","article-title":"Contribution of waste water treatment plants to pesticide toxicity in agriculture catchments","volume":"145","author":"Le","year":"2017","journal-title":"Ecotoxicol. Environ. Saf."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"360","DOI":"10.1016\/j.watres.2017.08.070","article-title":"Nanofiltration as tertiary treatment method for removing trace pharmaceutically active compounds in wastewater from wastewater treatment plants","volume":"125","author":"Martella","year":"2017","journal-title":"Water Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"204","DOI":"10.1016\/j.watres.2017.01.010","article-title":"Removal of antibiotic resistance genes from wastewater treatment plant effluent by coagulation","volume":"111","author":"Li","year":"2017","journal-title":"Water Res."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Gholizadeh, M.H., Melesse, A.M., and Reddi, L. (2016). A Comprehensive Review on Water Quality Parameters Estimation Using Remote Sensing Techniques. Sensors, 16.","DOI":"10.3390\/s16081298"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1021\/acs.analchem.7b04577","article-title":"Water Analysis: Emerging Contaminants and Current Issues","volume":"90","author":"Richardson","year":"2018","journal-title":"Anal. Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"203","DOI":"10.1021\/acs.analchem.5b04298","article-title":"Fiber-Optic Chemical Sensors and Biosensors (2013\u20132015)","volume":"88","author":"Wang","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"25208","DOI":"10.3390\/s151025208","article-title":"Fiber-optic chemical sensors and fiber-optic bio-sensors","volume":"15","year":"2015","journal-title":"Sensors"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Elosua, C., Arregui, F.J., Villar, I.D., Ruiz-Zamarre\u00f1o, C., Corres, J.M., Bariain, C., Goicoechea, J., Hernaez, M., Rivero, P.J., and Socorro, A.B. (2017). Micro and Nanostructured Materials for the Development of Optical Fibre Sensors. Sensors, 17.","DOI":"10.3390\/s17102312"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"12184","DOI":"10.3390\/s120912184","article-title":"Optical sensors based on plastic fibers","volume":"12","author":"Bilro","year":"2012","journal-title":"Sensors"},{"key":"ref_10","first-page":"194","article-title":"Polymer Fiber Optic Sensors\u2014A Mini Review of their Synthesis and Applications","volume":"7","author":"Jin","year":"2016","journal-title":"Biosens. Bioelectron."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"534","DOI":"10.1016\/j.snb.2016.10.104","article-title":"Intensity-based plastic optical fiber sensor with molecularly imprinted polymer sensitive layer","volume":"241","author":"Cennamo","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1016\/j.measurement.2018.04.088","article-title":"Plastic optical fiber immunosensor for fast detection of sulfate-reducing bacteria","volume":"125","author":"Lopes","year":"2018","journal-title":"Meas. J. Int. Meas. Confed."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1016\/j.snb.2015.05.007","article-title":"A molecularly imprinted polymer-based evanescent wave fiber optic sensor for the detection of basic red 9 dye","volume":"218","author":"Foguel","year":"2015","journal-title":"Sens. Actuators B Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1858","DOI":"10.1364\/OME.7.001858","article-title":"Room temperature ammonia sensor using side-polished optical fiber coated with graphene\/polyaniline nanocomposite","volume":"7","author":"Khalaf","year":"2017","journal-title":"Opt. Mater. Express"},{"key":"ref_15","unstructured":"Azkune, M., Ruiz-Rubio, L., Aldabaldetreku, G., Arrospide, E., P\u00e9rez-\u00c1lvarez, L., Bikandi, I., Zubia, J., and Vilas-Vilela, J. (2018). U-Shaped and Surface Functionalized Polymer Optical Fiber Probe for Glucose Detection. Sensors, 18."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"420","DOI":"10.1016\/j.snb.2009.01.064","article-title":"Simple dip-probe fluorescence setup sensor for in situ environmental determinations","volume":"137","author":"Rivera","year":"2009","journal-title":"Sens. Actuators B Chem."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"359","DOI":"10.1016\/j.bios.2014.09.017","article-title":"A disposable evanescent wave fiber optic sensor coated with a molecularly imprinted polymer as a selective fluorescence probe","volume":"64","author":"Ton","year":"2015","journal-title":"Biosens. Bioelectron."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Cennamo, N., D\u2019Agostino, G., Porto, G., Biasiolo, A., Perri, C., Arcadio, F., and Zeni, L. (2018). A molecularly imprinted polymer on a plasmonic plastic optical fiber to detect perfluorinated compounds in water. Sensors, 18.","DOI":"10.3390\/s18061836"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Cennamo, N., D\u2019Agostino, G., Sequeira, F., Mattiello, F., Porto, G., Biasiolo, A., Nogueira, R., Bilro, L., and Zeni, L. (2018). A simple and low-cost optical fiber intensity-based configuration for perfluorinated compounds in water solution. Sensors, 18.","DOI":"10.3390\/s18093009"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Sequeira, F., Duarte, D., Bilro, L., Rudnitskaya, A., Pesavento, M., Zeni, L., and Cennamo, N. (2016). Refractive Index Sensing with D-Shaped Plastic Optical Fibers for Chemical and Biochemical Applications. Sensors, 16.","DOI":"10.3390\/s16122119"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2007","DOI":"10.1364\/AO.53.002007","article-title":"Refractive index sensor based on plastic optical fiber with tapered structure","volume":"53","author":"Feng","year":"2014","journal-title":"Appl. Opt."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1673","DOI":"10.1109\/JSEN.2014.2301911","article-title":"D-Shaped Plastic Optical Fiber Sensor for Testing Refractive Index","volume":"14","author":"Feng","year":"2014","journal-title":"IEEE Sens."},{"key":"ref_23","first-page":"2902","article-title":"Side-Hole Plastic Optical Fiber for Testing Liquid\u2019s Refractive Index","volume":"15","author":"Liu","year":"2015","journal-title":"IEEE Sens. J."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"536","DOI":"10.1016\/j.snb.2016.02.074","article-title":"Development of LSPR based U-bent plastic optical fiber sensors","volume":"230","author":"Gowri","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1692","DOI":"10.1109\/JSEN.2016.2646802","article-title":"Refractive index sensor based on a multi-notched plastic optical fiber","volume":"17","author":"Tiwari","year":"2017","journal-title":"IEEE Sens. J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.yofte.2017.01.008","article-title":"Investigation of refractive index sensors based on side-polished plastic optical fibers","volume":"36","author":"Teng","year":"2017","journal-title":"Opt. Fiber Technol."},{"key":"ref_27","unstructured":"Sequeira, F., Duarte, D., Nogueira, R., Rudnitskaya, A., Cennamo, N., Zeni, L., and Bilro, L. (2016, January 13\u201315). Analysis of the roughness in a sensing region on D-shaped POFs. Proceedings of the 25th International Conference on Plastic Optical Fibers, Birmingham, UK."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1016\/j.optlastec.2017.10.006","article-title":"Sensitive zone parameters and curvature radius evaluation for polymer optical fiber curvature sensors","volume":"100","author":"Frizera","year":"2018","journal-title":"Opt. Laser Technol."},{"key":"ref_29","first-page":"253","article-title":"Polishing Process Analysis for Surface Plasmon Resonance Sensors in D-Shaped Plastic Optical Fibers","volume":"Volume 539","author":"Cennamo","year":"2019","journal-title":"Sensors. CNS 2018. Lecture Notes in Electrical Engineering"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/11\/2476\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:54:46Z","timestamp":1760187286000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/11\/2476"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,5,30]]},"references-count":29,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2019,6]]}},"alternative-id":["s19112476"],"URL":"https:\/\/doi.org\/10.3390\/s19112476","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,5,30]]}}}