14 February 2007 Low-loss integrated planar chalcogenide waveguides for microfluidic chemical sensing
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Chalcogenide glasses are an ideal material candidate for evanescent biochemical sensing due to their mid and far-infrared transparency. We have fabricated and tested, to the best of our knowledge, the first microfluidic device monolithically integrated with planar chalcogenide glass waveguides. High-index-contrast channel waveguides have been defined using plasma etching in thermally evaporated Ge23Sb7S70 films, followed by microfluidic channel patterning in photocurable resin (SU8) and channel sealing by a polydimethylsiloxane (PDMS) cover. Using this device, N-methylaniline can be detected using its well-defined absorption fingerprint of the N-H bond near 1496 nm. Our measurements indicate linear response of the sensor to varying N-methylaniline concentrations and a sensitivity of this sensor down to N-methylaniline concentration of 0.7 vol. %. Thermal reflow has been employed as an effective method to smooth chalcogenide waveguide sidewall roughness from 6.1 nm to 0.56 nm. Given the low-cost fabrication process and robust device configuration, our integration scheme provides a promising device platform for infrared chemical sensing applications.
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Juejun Hu, Vladimir Tarasov, Nathan Carlie, Rong Sun, Laeticia Petit, Anu Agarwal, Kathleen Richardson, Lionel Kimerling, "Low-loss integrated planar chalcogenide waveguides for microfluidic chemical sensing", Proc. SPIE 6444, Ultrasensitive and Single-Molecule Detection Technologies II, 64440N (14 February 2007); doi: 10.1117/12.696996; https://doi.org/10.1117/12.696996

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