{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,16]],"date-time":"2025-12-16T12:43:55Z","timestamp":1765889035442,"version":"build-2065373602"},"reference-count":9,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2023,1,3]],"date-time":"2023-01-03T00:00:00Z","timestamp":1672704000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Portuguese funding agency, FCT\u2014Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"],"award-info":[{"award-number":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"]}]},{"name":"FCT\/MCTES (PIDDAC)","award":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"],"award-info":[{"award-number":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"]}]},{"name":"Ministerio de Univesidades of Spain","award":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"],"award-info":[{"award-number":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"]}]},{"name":"MCIN\/AEI\/10.13039\/501100011033","award":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"],"award-info":[{"award-number":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"]}]},{"name":"MCIN\/AEI\/10.13039\/501100011033","award":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"],"award-info":[{"award-number":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"]}]},{"name":"FCT, Portugal","award":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"],"award-info":[{"award-number":["UIDB\/50014\/2020","LA\/P\/0045\/2020 (ALiCE)","UIDB\/00511\/2020","UIDP\/00511\/2020 (LEPABE)","PID2019-107270RB-C22","PDC2021-121172-C21","TED2021-130378B-C22","2020.05297.BD"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Photonics"],"abstract":"<jats:p>Process Analytical Technology (PAT) has been increasingly used in the pharmaceutical industry to monitor essential parameters in real-time during pharmaceutical processes. The concentration of Active Pharmaceutical Ingredients (APIs), such as paracetamol, is one of these parameters, and controlling its variations allows for optimization of the production process. In this study, a refractometric sensor, implemented by an interrogation system based on an Erbium-Doped Fiber Ring Cavity (EDFRC), was presented and experimentally demonstrated. The Cavity Ring proposed included a 1 \u00d7 3 coupler. One port of the coupler was used to increase the optical power of the system through a Fiber Bragg Grating (FBG), and the other two ports were used as sensing head and reference. The sensor detected variations of paracetamol concentration with a sensitivity of [(\u22121.00 \u00b1 0.05) \u00d7 10\u22123] nW\/(g\/kg) and a resolution of 5.53 g\/kg. The results demonstrate the potential of this technology as a possible non-invasive PAT tool.<\/jats:p>","DOI":"10.3390\/photonics10010050","type":"journal-article","created":{"date-parts":[[2023,1,4]],"date-time":"2023-01-04T02:54:55Z","timestamp":1672800895000},"page":"50","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Measurement of Paracetamol Concentration Using an Erbium-Doped Fiber Ring Cavity"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1828-4633","authenticated-orcid":false,"given":"Liliana","family":"Soares","sequence":"first","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, Rua do Campo Alegre 687, 4150-179 Porto, Portugal"},{"name":"Department of Engineering Physics, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6856-9143","authenticated-orcid":false,"given":"Rosa Ana","family":"P\u00e9rez-Herrera","sequence":"additional","affiliation":[{"name":"Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain"},{"name":"Institute of Smart Cities (ISC), Public University of Navarra, 31006 Pamplona, Spain"}]},{"given":"Susana","family":"Novais","sequence":"additional","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, Rua do Campo Alegre 687, 4150-179 Porto, Portugal"}]},{"given":"Ant\u00f3nio","family":"Ferreira","sequence":"additional","affiliation":[{"name":"LEPABE\u2014Laboratory for Process Engineering, Environment, Biotechnology and Energy, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"},{"name":"ALiCE\u2014Associate Laboratory in Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias s\/n, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7555-361X","authenticated-orcid":false,"given":"Susana","family":"Silva","sequence":"additional","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, Rua do Campo Alegre 687, 4150-179 Porto, Portugal"}]},{"given":"Orlando","family":"Fraz\u00e3o","sequence":"additional","affiliation":[{"name":"INESC TEC\u2014Institute for Systems and Computer Engineering, Technology and Science, Rua do Campo Alegre 687, 4150-179 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2023,1,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"699","DOI":"10.3109\/10837450.2015.1102278","article-title":"Monitoring the concentration of flowing pharmaceutical powders in a tableting feed frame","volume":"22","author":"Gosselin","year":"2017","journal-title":"Pharm. Dev. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.ejpb.2019.02.015","article-title":"Optimization of an in-line Raman spectroscopic method for continuous API quantification during twin-screw wet granulation and its application for process characterization","volume":"137","author":"Harting","year":"2019","journal-title":"Eur. J. Pharm. Biopharm."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Gao, Y., Zhang, T., Ma, Y., Xue, F., Gao, Z., Hou, B., and Gong, J. (2021). Application of PAT-Based Feedback Control Approaches in Pharmaceutical Crystallization. Crystals, 11.","DOI":"10.3390\/cryst11030221"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Kim, E.J., Kim, J.H., Kim, M.-S., Jeong, S.H., and Choi, D.H. (2021). Process Analytical Technology Tools for Monitoring Pharmaceutical Unit Operations: A Control Strategy for Continuous Process Verification. Pharmaceutics, 13.","DOI":"10.3390\/pharmaceutics13060919"},{"key":"ref_5","first-page":"30","article-title":"Process Analytical Technology: Tools and applications in pharmaceutical manufacturing","volume":"33","author":"Wiss","year":"2015","journal-title":"Chim. Oggi Chem. Today"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"110328","DOI":"10.1016\/j.measurement.2021.110328","article-title":"Progress, problems, and potential of technology for measuring solution concentration in crystallization processes","volume":"187","author":"Zhang","year":"2022","journal-title":"Measurement"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/B978-0-444-63963-9.00009-9","article-title":"Crystallization process monitoring and control using process analytical technology","volume":"Volume 41","author":"Singh","year":"2018","journal-title":"Process Systems Engineering for Pharmaceutical Manufacturing"},{"key":"ref_8","unstructured":"Hecht, E. (2015). Optics, Pearson. [5th ed.]."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Soares, L., Novais, S., Ferreira, A., Fraz\u00e3o, O., and Silva, O.S. (2019). Detection of the Crystallization Process of Paracetamol with a Multi-Mode Optical Fiber in a Reflective Configuration. Sensors, 20.","DOI":"10.3390\/s20010087"}],"container-title":["Photonics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2304-6732\/10\/1\/50\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T17:57:05Z","timestamp":1760119025000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2304-6732\/10\/1\/50"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,1,3]]},"references-count":9,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2023,1]]}},"alternative-id":["photonics10010050"],"URL":"https:\/\/doi.org\/10.3390\/photonics10010050","relation":{},"ISSN":["2304-6732"],"issn-type":[{"type":"electronic","value":"2304-6732"}],"subject":[],"published":{"date-parts":[[2023,1,3]]}}}