{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T17:39:31Z","timestamp":1792172371510,"version":"4.4.0"},"reference-count":43,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T00:00:00Z","timestamp":1775001600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100019349","name":"Universidad T\u00e9cnica Particular de Loja","doi-asserted-by":"crossref","award":["POA_VIN-56"],"award-info":[{"award-number":["POA_VIN-56"]}],"id":[{"id":"10.13039\/100019349","id-type":"DOI","asserted-by":"crossref"}]},{"award":["POA_VIN-56"],"award-info":[{"award-number":["POA_VIN-56"]}],"id":[{"id":"https:\/\/ror.org\/04dvbth24","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>A thin-film surface plasmon resonance (SPR) sensor is presented using a prism-coupled Kretschmann configuration and an optimized multilayer architecture incorporating black phosphorus (BP) as an ultrathin overlayer. The response is modeled at 633 nm under TM polarization using the transfer-matrix method. Low-concentration sensing conditions in the 1\u20135 ng\/mL range are represented through small effective-refractive-index perturbations of the aqueous sensing medium, providing a preliminary optical framework for evaluating refractive-index response in biosensing-related scenarios. The coupling prism, Au film thickness, and Si3N4 spacer thickness are optimized to control resonance depth, linewidth, and angular shift. The optimized CaF2\/Au\/Si3N4\/BP configuration exhibits systematic condition-dependent displacement of the SPR minimum and an evanescent-field distribution that remains strongly localized at the sensing interface while extending into the sensing medium, enabling refractive-index interrogation. High angular sensitivity is obtained at low levels, reaching 517.62\u00b0\/RIU at 2 ng\/mL and 482.82\u00b0\/RIU at 1 ng\/mL, with quality factors above 120 RIU\u22121 in the same regime. Composite indicators (figure of merit and contrast signal factor) peak at intermediate levels, whereas resonance broadening at higher levels reduces the quality factor and increases the inferred limit of detection, evidencing a sensitivity\u2013resolution trade-off. Benchmarking against reported SPR platforms indicates that BP-assisted interface engineering provides a competitive low-level operating window within a preliminary refractive-index-sensing framework that is relevant to future biosensor design. These results motivate further experimental validation, including BP stabilization, surface biofunctionalization, and practical implementation under liquid-phase sensing conditions.<\/jats:p>","DOI":"10.3390\/bios16040198","type":"journal-article","created":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T14:59:01Z","timestamp":1775055541000},"page":"198","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Modeling an SPR Sensor for Carcinoma-Related Refractive-Index Detection: The Case of CaF2\/Au\/Si3N4\/BP Multilayer System"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8588-6490","authenticated-orcid":false,"given":"Talia","family":"Tene","sequence":"first","affiliation":[{"name":"Department of Chemistry, Universidad T\u00e9cnica Particular de Loja, Loja 110160, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martha Ximena","family":"D\u00e1valos Villegas","sequence":"additional","affiliation":[{"name":"Facultad de Ciencias, Escuela Superior Polit\u00e9cnica de Chimborazo (ESPOCH), Panamericana Sur km. 1 1\/2, Riobamba 060155, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9248-9944","authenticated-orcid":false,"given":"Cristian","family":"Vacacela Gomez","sequence":"additional","affiliation":[{"name":"Department of Physics, University of Calabria, Via P. Bucci, Cubo 33C, 87036 Rende, Italy"},{"name":"Universidad Ecotec, Km. 13.5 Samborond\u00f3n, Samborond\u00f3n EC092302, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,1]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2023). Global Breast Cancer Initiative Implementation Framework: Assessing, Strengthening and Scaling Up of Services for the Early Detection and Management of Breast Cancer, World Health Organization. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789240065987."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Das, S., Dey, M.K., Devireddy, R., and Gartia, M.R. (2024). Biomarkers in Cancer Detection, Diagnosis, and Prognosis. 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