{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T05:05:51Z","timestamp":1789103151069,"version":"build-2803163510"},"reference-count":26,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T00:00:00Z","timestamp":1788825600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Electric Power Research Institute of State Grid Jiangsu Electric Power Co., Ltd.","award":["J2025071"],"award-info":[{"award-number":["J2025071"]}]},{"award":["J2025071"],"award-info":[{"award-number":["J2025071"]}],"id":[{"id":"https:\/\/ror.org\/02dqztz06","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Furfural is a pivotal indicator of the aging condition of transformer oil-paper insulation. Traditional analytical techniques such as liquid chromatography require sophisticated pretreatment and phase-separation procedures and are therefore not well suited to rapid oil-sample analysis. This study reports the direct analysis of furfural in complex oil mixtures using surface-enhanced Raman spectroscopy (SERS). The weak vibrational response of furfural in oil was enhanced using a Au-coated silicon nanowire substrate fabricated by metal-assisted chemical etching (MACE). The textured metal-coated surface enabled trace furfural at the \u03bcL\/L level to be measured directly in the oil mixture without adsorption enrichment or chemical extraction, with the entire test process completed within 1 min. Peak deconvolution was used to extract the fitted area of the 1365 cm\u22121 band, and the relationship between this Raman response and furfural concentration yielded R2 = 0.9910. Temperature- and pressure-dependent measurements were also performed to examine their effects on the positions of the main Raman peaks. This work demonstrates a rapid approach for analyzing trace furfural in complex liquid mixtures and provides a basis for further spectroscopic studies of transformer oil-paper insulation aging.<\/jats:p>","DOI":"10.3390\/s26185705","type":"journal-article","created":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T16:46:04Z","timestamp":1788885964000},"page":"5705","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["SERS-Enabled Direct Detection of Furfural in a Complex Oil Mixture"],"prefix":"10.3390","volume":"26","author":[{"given":"Xiaoqin","family":"Zhang","sequence":"first","affiliation":[{"name":"Electric Power Research Institute of State Grid Jiangsu Electric Power Co., Ltd., Nanjing 211103, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hongbin","family":"Zhu","sequence":"additional","affiliation":[{"name":"Electric Power Research Institute of State Grid Jiangsu Electric Power Co., Ltd., Nanjing 211103, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hao","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Engineering and Applied Sciences, Nanjing University, Nanjing 210026, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin","family":"Cao","sequence":"additional","affiliation":[{"name":"College of Engineering and Applied Sciences, Nanjing University, Nanjing 210026, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Han","family":"Shi","sequence":"additional","affiliation":[{"name":"College of Engineering and Applied Sciences, Nanjing University, Nanjing 210026, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shanyuan","family":"Niu","sequence":"additional","affiliation":[{"name":"College of Engineering and Applied Sciences, Nanjing University, Nanjing 210026, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Asl, M.B., Fofana, I., and Meghnefi, F. 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