Chemical reaction monitoring via the light focusing in optofluidic waveguides

Abstract

This paper studies the light focusing phenomenon in optofluidic waveguides and uses it to monitor chemical reactions. Firstly, the relationship between the light focusing pattern and its contributing factors is investigated experimentally. Next, a characterization experiment is conducted to validate the use of light focusing pattern as an indicator of diffusion properties. The sensitivity and the limit-of-detection (LOD) are measured to be 1.54 μm/(μm2/s) and 3.93 × 10−12 m2/s in the over-mixed region, respectively. Then, the sucrose hydrolysis reaction is monitored using the proposed optofluidic method as a demonstration. The initial hydrolysis rate of this reaction is measured to be 19.62 μM/min, which agrees reasonably well with the reported value. Lastly, this method is extended to determine the diffusion coefficient of binary solutions. The diffusion coefficients of ethylene glycol and glycerol in water are measured to be 5.56 ± 0.12 × 10-10 and 7.01 ± 0.20 × 10-10 m2/s, respectively. This study demonstrates a new method for potential integrated biochemical sensing and paves the way for a broad range of sensing applications in microreactors, chemical synthesis, and quantification of biomolecular interactions.