Browsing by Subject "Metal-enhanced fluorescence"

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    Micrometasense: coupling plasmonic metasurfaces with fluorescence for enhanced detection of microplastics in real samples
    (American Chemical Society, 2024-12-27) Ece, Emre; Aslan, Yusuf; Hacıosmanoglu, Nedim; İnci, Fatih
    Diverse analytical techniques are employed to scrutinize microplastics (MPs)-pervasive at hazardous concentrations across diverse sources ranging from water reservoirs to consumable substances. The limitations inherent in existing methods, such as their diminished detection capacities, render them inadequate for analyzing MPs of diminutive dimensions (microplastics: 1-5 mu m; nanoplastics: < 1 mu m). Consequently, there is an imperative need to devise methodologies that afford improved sensitivity and lower detection limits for analyzing these pollutants. In this study, we introduce a holistic strategy, i.e., MicroMetaSense, reliant on a metal-enhanced fluorescence (MEF) phenomenon in detecting a myriad size and types of MPs (i.e., poly(methyl methacrylate) (PMMA) and poly(ethylene terephthalate) (PET)) down to 183-205 fg, as well as validated the system with real samples (tap and lake) and artificial ocean samples as a real-world scenario. To obtain precise size distribution in nanometer scale, MPs are initially processed with an ultrafiltration on-a-chip method, and subsequently, the MPs stained with Nile Red dye are subjected to meticulous analysis under a fluorescence microscope, utilizing both a conventional method (glass substrate) and the MicroMetaSense platform. Our approach employs a metasurface to augment fluorescence signals, leveraging the MEF phenomenon, and it demonstrates an enhancement rate of 36.56-fold in detecting MPs compared to the standardized protocols. This low-cost ($2), time-saving (under 30 min), and highly sensitive (183-205 femtogram) strategy presents a promising method for precise size distribution and notable improvements in detection efficacy not only for laboratory samples but also in real environmental samples; hence, signifying a pivotal advancement in conventional methodologies in MP detection.
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    ItemOpen Access
    Possible plasmonic acceleration of LED modulation for Li-Fi applications
    (Springer New York LLC, 2018) Guzatov, D. V.; Gaponenko, S. V.; Demir, Hilmi Volkan
    Emerging LED-based wireless visible light communication (Li-Fi) needs faster LED response to secure desirable modulation rates. Decay rate of an emitter can be enhanced by plasmonics, typically by an expense of efficiency loss because of non-radiative energy transfer. In this paper, metal-enhanced radiative and non-radiative decay rates are shown to be reasonably balanced to get with Ag nanoparticles nearly 100-fold enhancement of the decay rate for a blue LED without loss in overall efficacy. Additionally, gain in intensity occurs for intrinsic quantum yield Q0 < 1. With silver, rate enhancement can be performed through the whole visible. For color-converting phosphors, local field enhancement along with decay rate effects enable 30-fold rate enhancement with gain in efficacy. Since plasmonics always enhances decay rate, it can diminish Auger processes thus extending LED operation currents without efficiency droop. For quantum dot phosphors, plasmonic diminishing of Auger processes will improve photostability.