Non-Invasive Measurement of Glucose Concentration Using Red and Near-Infrared Light-Emitting Diodes

Many diabetic mellitus patients envision a non-invasive method of blood glucose measurement since they require periodic monitoring of their blood glucose levels to ensure that it is stable and within the normal range. In this study, we detected glucose concentration using commercial light emitting diodes (LEDs) with a wavelength of 700–1600 nm. Light of long wavelengths (e.g. NIR) infiltrate human skin and reach the blood vessel lining, thereby aiding in the non-invasive measurement of blood glucose concentration. To demonstrate this, the concentration of glucose solutions was measured using red and NIR-LEDs in a non-invasive manner. The sensitivity of glucose detection was greater when light of wavelength below 1000 nm was used, owing to the absorption of wavelengths above 1000 nm by water. Furthermore, we controlled the input current of the red and NIR-LEDs to confirm the light intensity deviation with increasing glucose concentrations and suggested the optimum wavelength of light using this in-vitro system. Among various LEDs, the 700 nm LED showed higher light intensity deviation with change in injection current compared to LEDs with the other wavelengths. In particular, compared to other LEDs, a stark difference was observed in the light intensity of the 700 nm LED while measuring glucose concentrations in the range of 50–100 mg/dl.