title: Microfluidic refractometer with integrated optical fibers and end-facet transmission gratings.
abstract: We demonstrated a microfluidic refractometer with an integrated high resolution transmission grating. This grating was fabricated by UV nanoimprinting on the end facet of a multimode optical fiber which was then placed in the plan of the microfluidic device and perpendicular to a microchannel. On the opposite side of the channel, three cleaved optical fibers were added for the light collection of the zeroth and the +/- first diffraction orders. A white light source was used for illumination and the diffraction beams were analyzed with a minispectrometer. The transmission grating was merged in the sample solution of the channel, providing a refractive index-dependent diffraction efficiency. As expected, the diffraction efficiency of the zeroth and the +/- first diffraction orders are different, both being reliable for the refractive index monitoring. Such a white source and multibeam diffraction analysis also allows monitoring the sample absorption or fluorescence, thereby providing a more accurate determination of the sample refraction index.
authors.affiliation: Ecole Normal Supérieure, CNRS-ENS-UPMC UMR 8640, 24 rue Lhomond, Paris 75231, France.
authors.forename: Lei
authors.initials: L
authors.lastname: Lei
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Shi
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000042:Absorption; D046210:Microfluidic Analytical Techniques; D055100:Optical Fibers; D012031:Refractometry / Q000295:instrumentation*; D012235:Rhodamines / Q000737:chemistry; D013395:Sucrose / Q000737:chemistry
chemical_list: D012235:Rhodamines; C026188:rhodamine 6G; D013395:Sucrose