On-chip phase shift refractometer via microfluidic liquid grating

This paper describes the design, realization and testing of a refractometer based on the principle of transmission phase grating. An integrated multichannel microfluidic chip is used as a basic optical component for building the refractometer. A laser light beam is coupled to the top of the microfluidic chip and the generated diffraction pattern is recorded by a CCD camera and the intensities of the 0^th and plusmn1^st order are further analyzed. The microfluidic chip is fabricated using standard soft lithography technology. The realized refractometer has a refractive index resolution of 1.0 times 10^-5.