A Miniaturized Optofluidic Glucose Monitoring System Based on Enzyme Colorimetry

Continuous glucose monitoring is of great significance in the diagnosis and treatment of diabetes. In this paper, a miniaturized and automatic optofluidic system was designed for continuous glucose monitoring. Interstitial fluid (ISF) was first obtained by an ISF transdermal extracting chip. Then, the glucose concentration in the ISF was detected by enzyme colorimetry. For accurate detection of the glucose concentration, the volume of transdermally extracted ISF was measured, and the volumes of ISF and colorimetric reagent in the mixed sample were controlled and mixed uniformly. To test the precision and stability of the system, different concentrations of glucose solutions (30–200 mg/dL) were used to simulate ISF extracted from skin. The results revealed that the measured glucose concentration correlated well with the reference concentration (R
²
= 0.9976). In addition, the system achieved high-precision measurement of a low glucose concentration (30 mg/dL) even as the ISF volume fluctuated widely (0.5–
$2.5 ~\mu \text{L}$
), and the average absolute error was only 1.27%. Therefore, the system realized high precision for automatic and continuous monitoring of glucose in microvolume ISF samples, which would be a promising tool for the continuous monitoring of blood glucose concentration.