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Efficient transportation and delivery of analytes to the surface of optical sensors are crucial for overcoming limitations in diffusion-limited transport and analyte sensing. In this study, we propose a novel approach that combines metasurface optics with optofluidics-enabled active transport of extracellular vesicles (EVs). By leveraging this combination, we show that we can rapidly capture EVs and detect their adsorption through a color change generated by a specially designed optical metasurface that produces structural colors. Our results demonstrate that the integration of optofluidics and metasurface optics enables spectrometer-less and label-free colorimetric read-out for EV concentrations as low as 10⁷EVs/ml, achieved within a short incubation time of two minutes. 

Wavelength-selective thermal emitters (WS-EMs) hold considerable appeal due to the scarcity of cost-effective, narrow-band sources in the mid-to-long-wave infrared spectrum. WS-EMs achieved via dielectric materials typically exhibit thermal emission peaks with high quality factors (Qfactors), but their optical responses are prone to temperature fluctuations. Metallic EMs, on the other hand, show negligible drifts with temperature changes, but theirQfactors usually hover around 10. In this study, we introduce and experimentally verify an EM grounded in plasmonic quasi-bound states in the continuum (BICs) within a mirror-coupled system. Our design numerically delivers an ultra-narrowband single peak with aQfactor of approximately 64 and near-unity absorptance that can be freely tuned within an expansive band of more than 10 µm. By introducing air slots symmetrically, theQfactor can be further augmented to around 100. Multipolar analysis and phase diagrams are presented to elucidate the operational principle. Importantly, our infrared spectral measurements affirm the remarkable resilience of our designs’ resonance frequency in the face of temperature fluctuations over 300°C. Additionally, we develop an effective impedance model based on the optical nanoantenna theory to understand how further tuning of the emission properties is achieved through precise engineering of the slot. This research thus heralds the potential of applying plasmonic quasi-BICs in designing ultra-narrowband, temperature-stable thermal emitters in the mid-infrared. Moreover, such a concept may be adaptable to other frequency ranges, such as near-infrared, terahertz, and gigahertz. 

To address the challenges of developing a scalable system of an on-chip integrated quantum emitter, we propose to leverage the loss in our hybrid plasmonic-photonic structure to simultaneously achieve Purcell enhancement as well as on-chip maneuvering of nanoscale emitter via optical trapping with guided excitation-emission routes. In this report, we have analyzed the feasibility of the functional goals of our proposed system in the metric of trapping strength (∼8K_BT), Purcell factor (>1000∼), and collection efficiency (∼10%). Once realized, the scopes of the proposed device can be advanced to develop a scalable platform for integrated quantum technology.