The Model of near infrared sensor output voltage as a function of glucose concentration in solution

The number of people with diabetes increases every year in the whole world, including Indonesia. Diabetes is a major cause of stroke, heart attack, kidney failure, lower limb amputation and one of the leading causes of death. In order to manage their blood glucose level, diabetics have to test their blood glucose level as often as possible according to certain medical guidance, diet, exercise and consume medicine regularly. Unfortunately, the current blood glucose testing is inconvenient and uncomfortable, even cause pain for diabetic or patient; therefore, a noninvasive blood glucose measurement is highly desirable. Although several research works have already been done in this area, a successful noninvasive method is still in search. In order to contribute in this research area, we study the effect of glucose concentration in solutions with different concentration to the output voltage of a near infrared sensor as a preliminary research to obtain a successful noninvasive blood glucose meter. In this paper, we reported the model of near infrared sensor output voltage as a function of glucose concentration. The main components of the near infrared sensor are a 1450 nm light emitting diode (LED) as light source, and a photodiode that is sensitive to that wavelength as the sensing device. The distance between LED and photodiode is 15mm. The solutions have 50 mg/dl, 100 mg/dl, 200 mg/dl, 300 mg/dl, and 400 mg/dl glucose concentrations. An acrylic cylinder with 40 mm diameter was filled with 5 ml glucose solution for each concentration. The results show that higher glucose concentrations produce lower sensor output voltages. The linear trend line shows good fit with those data. The value of correlation coefficient is -0.99, which indicates strong relationship between the sensor output voltages and glucose concentrations.