{
  "abstract": "Integrated photonic sensors offer a pathway toward compact chemical analysis, but their use in unprocessed complex fluids is limited by surface fouling, chemical compatibility, and the need for stable optical coupling. Here, we develop a reusable waveguide-enhanced Raman spectroscopy (WERS) platform based on chemically resilient silicon nitride waveguides and a permanently packaged fiber-to-chip interface. The sensor incorporates a spiral sensing waveguide and a robust optical input/output architecture designed to provide reproducible coupling without active alignment. Reusability was evaluated following exposure to commercial gasoline and sequential cleaning treatments. Raman signal recovery using isopropanol as a reference analyte demonstrated improved spectral performance after solvent and oxidative cleaning. As a representative application in a chemically complex matrix, the sensor was directly immersed in commercial gasoline for quantitative ethanol determination without extraction or additional sample preparation. A ratiometric signal based on the ethanol band at 885 cm-1 and a reference band at 1000 cm-1 provided a linear calibration over 10.00–21.74% v/v ethanol (R2 = 0.9323). Independent external validation across 10.00–20.00% v/v yielded 100% prediction-interval coverage, an RMSEP of 0.46% v/v, and an MAE of 0.36% v/v. These results demonstrate that chemically robust WERS with stable packaging can support reproducible, reusable Raman sensing directly in complex fuel matrices, providing a foundation for field-deployable photonic chemical analysis.",
  "abstract_shown": true,
  "affiliations": [
    "Department of Materials Science and Engineering",
    "Massachusetts Institute of Technology",
    "InSpek SAS, 73 rue Léon Bourgeois, Palaiseau, France, 91120"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Lamyaa M. Almehmadi",
      "orcid": "0000-0002-2572-9733"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Tushar S. Karnik"
    },
    {
      "affs": [
        2
      ],
      "name": "Jérôme Michon"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Juejun Hu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/f8s6xg7c69wqs.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15010508/v1",
  "fulltext_url": null,
  "id": "f8s6xg7c69wqs",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010508/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2208|Photonic and Optical Devices"
    ]
  ],
  "openalex": "W7221950842",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15010508/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-15",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/f8s6xg7c69wqs.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:24Z",
      "native_id": "10.26434/chemrxiv.15010508",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010508/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "source:chemrxiv",
      "subfield": "general"
    }
  ],
  "title": "Robust and Reusable Waveguide-Enhanced Raman-on-a-Chip for Sensing Complex Fluids",
  "title_text": "Robust and Reusable Waveguide-Enhanced Raman-on-a-Chip for Sensing Complex Fluids",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:24Z",
  "url": "https://research.draconitic.com/paper/f8s6xg7c69wqs",
  "venue": "ChemRxiv",
  "versions": []
}