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The adsorption of a guest molecule modifies the effective refractive index of ZIF-8 through pore-filling effects, rendering it appropriate for optical sensing. In the present study, we investigate the design of a reflective tip-based tapered fiber optic surface plasmon resonance (FO-SPR) platform functionalized with a ZIF-8 absorbing layer for the detection of chemical vapors. Experimentally measured, analyte-dependent refractive index changes of ZIF-8 are integrated into a Transfer Matrix Method (TMM) based reflective tapered FO-SPR model to systematically evaluate the influence of taper ratio on resonance wavelength, sensitivity, spectral broadening, and figure of merit for different vapor analytes. The analyte-dependent response towards tetrahydrofuran (THF), ethanol, and dimethylformamide (DMF) is analysed in terms of the refractometric modulation characteristics of ZIF-8 using the SPR transduction mechanism. To the best of our knowledge, this study constitutes the first theoretical investigation of MOF pore-filling dynamics within a reflective-tapered FO-SPR configuration. The sensor performance enhances significantly as the taper diameter decreases from 600\u00a0to 200\u00a0\u03bcm with sensitivity increasing from 9.38 to 10.76\u00a0nm\/Volume Factor for THF and from 4.83 to 5.69\u00a0nm\/Volume Factor for DMF. The operating range of the sensor is governed by the effective refractive index tunability of the ZIF-8 layer, which varies from 1.355 to 1.421, ensuring conditions necessary for SPR excitation relative to the fiber core. These results establish a fundamental framework for optical refractometric vapour sensing and provide practical design guidelines for MOF-functionalized tapered FO-SPR platforms.<\/jats:p>","DOI":"10.1038\/s41598-026-61422-9","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T15:36:43Z","timestamp":1783438603000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Metal organic framework functionalized reflective tapered fibre-optic surface plasmon resonance based refractometer for vapor sensing"],"prefix":"10.1038","volume":"16","author":[{"given":"Akila","family":"Chithravel","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naveen","family":"Ilango","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jain","family":"Jacob","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jithin","family":"John","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lakkakula","family":"Satish","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandeep","family":"Munjal","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sruthi P.","family":"Usha","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anand M.","family":"Shrivastav","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,7,7]]},"reference":[{"key":"61422_CR1","doi-asserted-by":"publisher","first-page":"214","DOI":"10.1080\/02726340801921650","volume":"28","author":"I Abdulhalim","year":"2008","unstructured":"Abdulhalim, I., Zourob, M. & Lakhtakia, A. 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