n112398SE Academic Article uri icon

abstract

  • A mid-infrared (mid-IR) spectrometer for label-free on-chip chemical sensing was developed using an engineered nanofluidic channel consisting of a Si-liquid-Si slot-structure. Utilizing the large refractive index contrast (n 2) between the liquid core of the waveguide and the Si cladding, a broadband mid-IR lightwave can be efficiently guided and confined within a nanofluidic capillary (100 nm wide). The optical-field enhancement, together with the direct interaction between the probe light and the analyte, increased the sensitivity for chemical detection by 50 times when compared to evanescent-wave sensing. This spectrometer distinguished several common organic liquids (e.g., n-bromohexane, toluene, isopropanol) accurately and could determine the ratio of chemical species (e.g., acetonitrile and ethanol) at low concentration (<5 L/mL) in a mixture through spectral scanning over their characteristic absorption peaks in the mid-IR regime. The combination of CMOS-compatible planar mid-IR microphotonics, and a high-throughput nanofluidic sensor system, provides a unique platform for chemical detection.

published proceedings

  • Nano Lett

author list (cited authors)

  • Lin, P. T., Kwok, S. W., Lin, H., Singh, V., Kimerling, L. C., Whitesides, G. M., & Agarwal, A.

publication date

  • January 1, 2014 11:11 AM