Chemical reaction monitoring using tunable optofluidic Y-branch waveguides developed with counter-flow

Abstract

Chemical reaction monitoring based on integrated optofluidic systems is highly desirable because it is simpler, more flexible and efficient compared to traditional optical spectroscopy technique. This paper reports a novel chemical microreactor which is developed with a tunable optofluidic Y-branch waveguide, and this work demonstrates the monitoring of the sucrose hydrolysis reaction process by detecting the ratio of the two output intensities of light. The optofluidic Y-branch waveguide is formed by a liquid-core/liquid-cladding configuration with counter-flows. With the sucrose hydrolyzed into glucose and fructose in the waveguide core, the average molecular size of the product changes, which leads to the change of diffusion coefficient and the refractive index distribution profile. Therefore, the two output intensities of light change accordingly. Experimental studies have well demonstrated that the optofluidic Y-branch waveguide can monitor the sucrose hydrolysis in the concentration range from 0 to 2.1 mol/L with a limit of detection (LOD) of 250 μmol/L. This integrated optofluidic device can be used for various sensing applications in chemical reaction monitoring and quantification of molecular interactions with shortened test time and small sample volume.