{"doi":"10.1109/jsen.2021.3111125","title":"Exploring the Synergy of Radiative Coupling and Substrate Undercut in Arrayed Gold Nanodisks for Economical, Ultra-Sensitive Label-Free Biosensing","abstract":"We report radiatively coupled arrayed gold nanodisks on invisible substrate (AGNIS) as a cost-effective, high-performance platform for nanoplasmonic biosensing. By substrate undercut, the electric field distribution around the nanodisks has been restored to as if the nanodisks were surrounded by a single medium, thereby provides analyte accessibility to otherwise buried enhanced electric field. The AGNIS substrate has been fabricated by wafer-scale nanosphere lithography without the need for costly lithography. The LSPR blue-shifting behavior synergistically contributed by radiative coupling and substrate undercut have been investigated for the first time, which culminates in a remarkable refractive index sensitivity increase from 207 nm/RIU to 578 nm/RIU. The synergy also improves surface sensitivity to monolayer neutravidin-biotin binding from 7.4 nm to 20.3 nm with the limit of detection (LOD) of neutravidin at 50 fM, which is among the best label-free results reported to date on this specific surface binding reaction. As a potential cancer diagnostic application, extracellular vesicles such as exosomes excreted by cancer and normal cells were measured with a LOD within 112–600 (exosomes/ <inline-formula xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"> <tex-math notation=\"LaTeX\">$\\mu \\text{L}$ </tex-math></inline-formula> ), which would be sufficient in many clinical applications. Using CD9, CD63, and CD81 antibodies, label-free profiling has shown increased expression of all three surface antigens in cancer-derived exosomes. This work demonstrates, for the first time, strong synergy of arrayed radiative coupling and substrate undercut can enable economical, ultrasensitive biosensing in the visible light spectrum where high-quality, low-cost silicon detectors are readily available for point-of-care applications.","journal":"IEEE Sensors Journal","year":2021,"id":199386,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":9,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9529,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":775858,"name":"Nareg Ohannesian","orcid":"0000-0003-3132-2558","position":1,"is_corresponding":false},{"id":340612,"name":"Yawei Qiao","orcid":null,"position":2,"is_corresponding":false},{"id":236019,"name":"Steven H. Lin","orcid":"0000-0003-4411-0634","position":3,"is_corresponding":false},{"id":775859,"name":"Wei‐Chuan Shih","orcid":"0000-0002-7530-7352","position":4,"is_corresponding":false},{"id":775857,"name":"Ibrahim Misbah","orcid":"0000-0002-6397-2240","position":0,"is_corresponding":true}],"reference_count":53,"raw_metadata":null,"created_at":"2026-07-18T23:50:40.558460Z","pmid":"34970084","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}