Harnessing the unprecedented spatiotemporal resolution capability of light to detect electrophysiological signals has been the goal of neuroscientists for nearly 50 years. Yet, progress towards that goal remains elusive due to lack of electro-optic translators that can efficiently convert bioelectronic signals to high photon-count optical signals. Here, we introduce an ultrasensitive and extremely bright field-effect active plasmonic nanoantenna translating tiny electric field oscillations to large optical signals in the far-field. Our electrochromically loaded plasmonic nanoprobes overcome the limitation of state-of-art neuroelectrode technologies and enable massively multiplexed measurement of nanoscale electric-field modulations. In our experiments, we demonstrated 500 million parallel, ultrasensitive and subcellular resolution recordings of cell firing behavior, reflecting a technical capability that is well beyond the theoretical limits of the state-of-art neurotechnologies.
Harnessing the unprecedented spatiotemporal resolution capability of light to detect electrophysiological signals has been the goal of scientists for nearly 50 years. Advancements in this field could open new frontiers in neuroscience, cardiology and cellular biology. Yet, progress towards that goal remains elusive due to lack of electro-optic translators that can efficiently convert electrical activity to high photon-count optical signals. Here, we introduce an ultrasensitive and extremely bright nanoscale electric-field probe. Our electro-active plasmonic nanoantenna, offering ~3.25x10^3 times enhanced electric-field sensitivities than conventional plasmonic nanoantennas, overcomes the low sensitivity and photon-count limitations, and enables us to realize optical detection of electric-field dynamics with signal-to-shot-noise ratios (SSNR~ 60-220) from diffraction limited spots. We demonstrate label-free optical recording of field dynamics with sub-millisecond temporal resolution.
KEYWORDS: Aluminum, Plasmonics, Bacteria, Visible radiation, Nanoantennas, Near field optics, Near field, Pathogens, Ultraviolet radiation, Detection and tracking algorithms
405 nm light is emerging as a safe alternative to UV light for light-based continuous inactivation of drug resistant bacteria in high risk environments (i.e., hospitals). LED manufacturers are introducing 405-nm room lighting solutions for this purpose. However, inactivation efficiencies of commercial 405-nm technologies are still few orders of magnitude lower than those of UV light. Here, we achieve light 500-fold increased inactivation efficiencies with 405-nm light using radiatively coupled aluminum plasmonic nanoantenna arrays and demonstrated nearly complete deactivation of bacteria (%99,995). Our inactivation scheme opens door to continously self-cleaning surface coatings killing multi-drug resistance bacteria using ambient/room lighting.
We introduce Optofluidic PlasmonIC (OPtIC) microlenses to overcome the shortcomings of existing optical chromatography techniques by eliminating the need for sophisticated instrumentation and pre- cise alignment requirements. Our sub-wavelength thick (~200 nm thick) OPtIC microlenses offer objective-free focusing and self-alignment of optical and fluidic drag forces and present a facile platform for selective separation of exosome size bioparticles. By allowing direct coupling of collimated broadband light to realize strong optical scattering forces at a focal point, extremely small footprint (4 μm × 4 μm) OPtIC microlenses open the door for drastically multiplexed optical chromatography and high-throughput sample processing capability.
We introduce a subwavelength thick (~ 200 nm) plasmofluidic microlens that effortlessly achieves objective-free focusing and self-alignment of opposing optical scattering and fluidic drag forces for selective separation of exosome size bioparticles. Our optofluidic microlens provides a self-collimating mechanism for particle trajectories with a spatial dispersion that is inherently minimized by the optical gradient and radial fluidic drag forces. We demonstrate that this facile platform facilitates complete separation of small size bioparticles (i.e., exosomes) from a heterogenous mixture through negative depletion and provides a robust selective separation capability based on differences in chemical composition (refractive index). Unlike existing optical chromatography techniques that require complicated instrumentation (lasers, objectives and precise alignment stages), our platform open up the possibility of multiplexed and high-throughput sorting of nanoparticles on a chip.
We demonstrate that patches of two dimensional arrays of circular plasmonic nanoholes patterned on gold-titanium thin film enables subwavelength focusing of visible light in far field region. Efficient coupling of the light with the excited surface plasmon at metal dielectric interface results in strong light transmission. As a result, surface plasmon plays an important role in the far field focusing behavior of the nanohole-aperture patches device. Furthermore, the focal length of the focused beam was found to be predominantly dependent on the overall size of the patch, which is in good agreement with that calculated by Rayleigh-Sommerfield integral formula. The focused light beam can be utilized to separate bio-particles in the dynamic range from 0.1 μm to 1 μm through mainly overcoming the drag force induced by fluid flow. In our proposed model, focused light generated by our plasmonic lenses will push the larger bio-particles in size back to the source of fluid flow and allow the smaller particles to move towards the central aperture of the patch. Such a new kind of plasmonic lenses open up possibility of sorting bacterium-like particles with plasmonic nanolenses, and also represent a promising tool in the field of virology.
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