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Particulate-based structures for nanoscale imaging and sensing (Conference Presentation)

Three major challenges in biological sensing and imaging systems are to improve sensitivity, resolution, and throughput. In this talk, I present results on using structures seeded or constructed by nanoparticles to provide enhancements in these three areas. We present our work in two parts. First, we have used vapor-deposited liquid nanoscale polyethylene glycol lenses to aid in sensing nanoscale particles that serve as seeds for these nanolenses. This approach is combined with lensfree holographic microscopy to image a transparent sample slide with adsorbed nanoparticles. Lensfree holographic microscopy provides an ultra-large field of view >20 mm^2 together with submicron resolution, however its sensitivity to nanoparticles is limited and particles smaller than ~300 nm cannot be inherently distinguished from background noise. The liquid nanolenses we deposit significantly enhance the sensitivity of this system such that >10^5 particles as small as 40 nm can be individually detected, localized, and sized. The second part of this talk focuses on using optical tweezers to assemble nanophotonic structures out of heterogeneous colloidal nanoparticles. The resulting structures can provide superresolution based on transmission line and metamaterial physical principles. Optically-positioned nanoparticles can also be attached to whispering gallery mode microresonators to enhance their sensitivity and facilitate free-space coupling. Finally, we have investigated the speed with which we can position nanoparticles using optical tweezers, and have measured maximum manipulation rates in excess of 150 um/s, which makes optical tweezers a viable approach for rapid prototyping additive manufacturing of nanophotonic structures.