Label-Free Early Pregnancy Detection Using a ZBLAN Prism-Based Surface Plasmon Resonance Biosensor

Label-Free Early Pregnancy Detection Using a ZBLAN Prism-Based Surface Plasmon Resonance Biosensor | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Label-Free Early Pregnancy Detection Using a ZBLAN Prism-Based Surface Plasmon Resonance Biosensor Khandoker Tauhid Imam, Nayeema Rouf Nobonita, H. M. Ibrahim Khalil, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8205359/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Feb, 2026 Read the published version in Sensing and Imaging → Version 1 posted 11 You are reading this latest preprint version Abstract Early pregnancy detection is critical for timely prenatal care and for reducing maternal fetalcomplications. We propose a highly sensitive surface plasmon resonance (SPR) biosensor inthe Kretschmann configuration using a ZBLAN prism, a Cu plasmonic film, a ZnS dielectricspacer, and a two-dimensional black phosphorus (BP) overlayer. This multilayer architecturestrengthens analyte–surface interaction and localizes the plasmonic field at resonance.Thedevice attains a sensitivity up to 600 ◦/RIU over the analyte refractive-index range 1.340–1.342.Additional performance metrics include a minimum full width at half maximum (FWHM) of4.6607◦, a maximum figure of merit (FoM) of 115.75 RIU−1, and a limit of detection (LoD)as low as 3.4 × 10−5 RIU. Field analysis further shows a maximum electric-field amplitude ofabout 401.283 kV m−1 at the BP/analyte interface and an evanescent-field penetration depthof approximately 151.5 nm. These results position the proposed biosensor as a promisingcandidate for real-time, label-free, and highly sensitive early-pregnancy detection suitable forboth clinical and home-based diagnostics. Early pregnancy detection Surface plasmon resonance (SPR) ZBLAN prism dielectric spacer Multilayer biosensor Transfer Matrix Method (TMM) Finite Element Method (FEM) Lowcost optical sensor Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 25 Feb, 2026 Read the published version in Sensing and Imaging → Version 1 posted Editorial decision: Revision requested 21 Jan, 2026 Reviews received at journal 20 Jan, 2026 Reviews received at journal 14 Jan, 2026 Reviewers agreed at journal 08 Jan, 2026 Reviewers agreed at journal 08 Jan, 2026 Reviewers agreed at journal 07 Jan, 2026 Reviewers agreed at journal 07 Jan, 2026 Reviewers invited by journal 07 Jan, 2026 Editor assigned by journal 10 Dec, 2025 Submission checks completed at journal 02 Dec, 2025 First submitted to journal 25 Nov, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8205359","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":571607376,"identity":"7193138d-e002-4009-b385-1f4cb33cec24","order_by":0,"name":"Khandoker Tauhid Imam","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYHACNoYENhDNfAAqkIBfPQ9CCxtIqQGRWhjAWngMiNNiz37G7MGDMgY5fvaej595/vxh4GfPMcBvC0+OuUHCOQZjyZ6zm6V52wwYJHveENDCkGMmkdjGkLjhRu4Gad4GAwaDG4Rs4X8D1lK///6bx795/hgw2BPUIgGxJcFAgodNmocNaIsEIS03npVJJJyTMJxxJs3Mcm6bMY/EmWcFeLWw9ydvk/xRZiPP33748Y03f+Tk+NuTN+DVAgUSCGuJUT4KRsEoGAWjgAAAAFjgPQFb3WaJAAAAAElFTkSuQmCC","orcid":"","institution":"Ahsanullah University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Khandoker","middleName":"Tauhid","lastName":"Imam","suffix":""},{"id":571607378,"identity":"4d4f7e6e-aa17-4dce-b252-6807349a3143","order_by":1,"name":"Nayeema Rouf Nobonita","email":"","orcid":"","institution":"Ahsanullah University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Nayeema","middleName":"Rouf","lastName":"Nobonita","suffix":""},{"id":571607379,"identity":"f640f9a5-619b-49ea-9554-76b2e2f184f3","order_by":2,"name":"H. 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