Optical and electronic signal stabilization of plasmonic fiber optic gate electrodes: Towards improved real-time dual-mode biosensing Hasler, Roger Steger-Polt, Marie Helene Reiner-Rozman, Ciril Fossati, Stefan Lee, Seungho ; https://orcid.org/0000-0002-6962-8598 Aspermair, Patrik Kleber, Christoph Ibáñez, Maria ; https://orcid.org/0000-0001-5013-2843 Dostalek, Jakub Knoll, Wolfgang ddc:530 The use of multimodal readout mechanisms next to label-free real-time monitoring of biomolecular interactions can provide valuable insight into surface-based reaction mechanisms. To this end, the combination of an electrolyte-gated field-effect transistor (EG-FET) with a fiber optic-coupled surface plasmon resonance (FO-SPR) probe serving as gate electrode has been investigated to deconvolute surface mass and charge density variations associated to surface reactions. However, applying an electrochemical potential on such gold-coated FO-SPR gate electrodes can induce gradual morphological changes of the thin gold film, leading to an irreversible blue-shift of the SPR wavelength and a substantial signal drift. We show that mild annealing leads to optical and electronic signal stabilization (20-fold lower signal drift than as-sputtered fiber optic gates) and improved overall analytical performance characteristics. The thermal treatment prevents morphological changes of the thin gold-film occurring during operation, hence providing reliable and stable data immediately upon gate voltage application. Thus, the readout output of both transducing principles, the optical FO-SPR and electronic EG-FET, stays constant throughout the whole sensing time-window and the long-term effect of thermal treatment is also improved, providing stable signals even after 1 year of storage. Annealing should therefore be considered a necessary modification for applying fiber optic gate electrodes in real-time multimodal investigations of surface reactions at the solid-liquid interface. Frontiers 2023 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/13968 https://research-explorer.ista.ac.at/download/13968/13978 Hasler R, Steger-Polt MH, Reiner-Rozman C, et al. Optical and electronic signal stabilization of plasmonic fiber optic gate electrodes: Towards improved real-time dual-mode biosensing. <i>Frontiers in Physics</i>. 2023;11. doi:<a href="https://doi.org/10.3389/fphy.2023.1202132">10.3389/fphy.2023.1202132</a> eng info:eu-repo/semantics/altIdentifier/doi/10.3389/fphy.2023.1202132 info:eu-repo/semantics/altIdentifier/e-issn/2296-424X info:eu-repo/semantics/altIdentifier/wos/001038636400001 https://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess