16 February 2010 Sub-wavelength plasmonic readout for direct linear analysis of optically tagged DNA
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Proceedings Volume 7577, Plasmonics in Biology and Medicine VII; 75770Q (2010) https://doi.org/10.1117/12.841165
Event: SPIE BiOS, 2010, San Francisco, California, United States
This work describes the development and fabrication of a novel nanofluidic flow-through sensing chip that utilizes a plasmonic resonator to excite fluorescent tags with sub-wavelength resolution. We cover the design of the microfluidic chip and simulation of the plasmonic resonator using Finite Difference Time Domain (FDTD) software. The fabrication methods are presented, with testing procedures and preliminary results. This research is aimed at improving the resolution limits of the Direct Linear Analysis (DLA) technique developed by US Genomics [1]. In DLA, intercalating dyes which tag a specific 8 base-pair sequence are inserted in a DNA sample. This sample is pumped though a nano-fluidic channel, where it is stretched into a linear geometry and interrogated with light which excites the fluorescent tags. The resulting sequence of optical pulses produces a characteristic "fingerprint" of the sample which uniquely identifies any sample of DNA. Plasmonic confinement of light to a 100 nm wide metallic nano-stripe enables resolution of a higher tag density compared to free space optics. Prototype devices have been fabricated and are being tested with fluorophore solutions and tagged DNA. Preliminary results show evanescent coupling to the plasmonic resonator is occurring with 0.1 micron resolution, however light scattering limits the S/N of the detector. Two methods to reduce scattered light are presented: index matching and curved waveguides.
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Jonathan Varsanik, Jonathan Varsanik, William Teynor, William Teynor, John LeBlanc, John LeBlanc, Heather Clark, Heather Clark, Jeffrey Krogmeier, Jeffrey Krogmeier, Tian Yang, Tian Yang, Kenneth Crozier, Kenneth Crozier, Jonathan Bernstein, Jonathan Bernstein, } "Sub-wavelength plasmonic readout for direct linear analysis of optically tagged DNA", Proc. SPIE 7577, Plasmonics in Biology and Medicine VII, 75770Q (16 February 2010); doi: 10.1117/12.841165; https://doi.org/10.1117/12.841165

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