Development of non-invasive blood glucose levelmeasurement system with infrared light

In this thesis, a near-infrared (NIR) based LED sensor circuit has been developed to achieve a non-invasive method as an alternative for measuring blood glucose level. The system used 940 nm wavelength NIR LEDs. The analog signal was transmitted through a filter and an amplifier circuit. Then, it was converted to a digital signal where the output voltage was measured, and the glucose level was calculated using an Arduino UNO. In the in vitro test, it was observed that the output voltage changes with changing concentrations of glucose solution, and there was a good correlation between the two variables, and this motivated the in vivo test. We have executed our experiment according to three scenarios: (i) Certain amount of glucose is dissolved in water and the glucose concentration is measured by our equipment, (ii) 5-cm3 blood sample of participants is taken and the blood glucose level is measured in a test tube by our apparatus and then this sample is moved to the gold-standard equipment and the actual value of blood glucose level is measured. The measured voltage versus blood glucose level in our designed optical equipment indicates a fairly linear relation between them. (iii) blood glucose level is measured over the fingertip and compared to the gold-standard value. In this case, the measurement error does not exceed 25% and the voltage change with respect to the blood glucose level shows a nonlinear behavior. The designed system has a low cost and provides an acceptable error, making it suitable to be commercialized for diabetic patients.