A microfluidic optical sensor utilizes at least one subwavelength nanowire or nanoribbon waveguide coupled to a fluidic structure having at least one nanofluidic channel through which one or more molecular species are conveyed. In response to optical pumping (e.g., a laser source) the waveguide optically interrogates nearby molecular species retained within said fluidic structure to detect chemical species in response to optical characterization of small (on the order of sub-picoliter) volumes of solution. Characterization is performed in response to evanescent wave sensing. In one aspect, optical characterization is selected from the group of optical characterizations consisting of absorbance, fluorescence and surface enhanced Raman spectroscopy (SERS).
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with Government support under Contract No. DE-FG02-02ER-46021 awarded by the Department of Energy, Grant No. DE-AC02-05CH11231 awarded by the Department of Energy. The Government has certain rights in this invention.