Fig. 1: Characterization of a smart contact lens for monitoring tear glucose.

a Schematic illustration of a plasma leakage in human eyes. Red arrows indicate the leakage of glucose from blood into the tear film. b Schematic illustration of the tear glucose (TG) monitoring system using the smart contact lens (SCL) and smart phone. c Schematic illustration of the electrochemical glucose biosensor with two electrodes and magnified electrochemical reaction layer of working electrode. d Relative changes in current at various concentrations of glucose. e Calibration curve of the relative changes in current as a function of glucose concentration (n = 20). Each data point represents the average of 20 samples, and the error bars indicate mean ± standard error of the mean. f Schematic illustration of the serpentine antenna and the capacitor integrated to the antenna pad. g The resonance frequency of the serpentine antenna integrated into the SCL. h Circuit diagram of the SCL system for the wireless monitoring of the glucose level.