A non-invasive microcontroller based estimation of blood glucose concentration by using a modified capacitive sensor at low frequency

In the present work, a noninvasive technique of glucose concentration measurement in human blood has been developed. A semicylindrical capacitive sensor is used to measure the blood glucose concentration in terms of capacitance of the sensor. It is shown that this capacitance varies linearly with glucose concentration in human blood. A low frequency operational amplifier based circuit is designed to measure this capacitance in terms of an output voltage signal. A linear relation between the ratio of this output signal to input supply with blood glucose concentration is derived in the paper. A microcontroller based software program is designed to measure this ratio and to display glucose concentration in a LCD display unit in digital form. The performance study of the proposed blood glucose concentration measurement circuit with respect to standard glucometer and that of the proposed blood glucose concentration display unit are carried out in the present work. The experimental results are reported in the paper in both tabular and graphical forms. The linear characteristic graphs and close conformity of the results of the proposed technique with those of standard glucometer are observed. The measurement error with respect to glucometer is found to be within ±3.5%.