An enzymatic microreactor based on chaotic micromixing for enhanced amperometric detection in a continuous glucose monitoring application.

The development of continuous glucose monitoring systems is a major trend in diabetes-related research. Small, easy-to-wear systems which are robust enough to function over many days without maintenance are the goal. We present a new sensing system for continuous glucose monitoring based on a microreactor incorporating chaotic mixing channels. Two different types of chaotic mixing channels with arrays of either slanted or herringbone grooves were fabricated in poly(dimethylsiloxane) (PDMS) and compared to channels containing no grooves. Mixing in channels with slanted grooves was characterized using a fluorescence method as a function of distance and at different flow rates, and compared to the mixing behavior observed in channels with no grooves. For electrochemical detection, a thin-film Pt electrode was positioned at the end of the fluidic channel as an on-chip detector of the reaction product, H(2)O(2). Glucose determination was performed by rapidly mixing glucose and glucose oxidase (GOx) in solution at a flow rate of 0.5 microL/min and 1.5 microL/min, respectively. A 150 U/mL GOx solution was selected as the optimum concentration of enzyme. In order to investigate the dependence of device response on flow rate, experiments with a premixed solution of glucose and GOx were compared to experiments in which glucose and GOx were reacted on-chip. Calibration curves for glucose (0-20 mM, in the clinical range of interest) were obtained in channels with and without grooves, using amperometric detection and a 150 U/mL GOx solution for in-chip reaction.