Impedance based Monitoring

various parameters that influence the measurements are the influence of environmental/body temperature changes, changes in the blood perfusion of the skin under test or blood flux, underlying tissue volume and changes in the contacts of sensor / skin due to movements. the relation ship between the change in glucose concentration and the impedance of skin underlying tissue has the positive correlation [1].

In order to avoid the interferences, the following sensors are used:capacitive fringing field electrodes, inter-digitated electrodes for impedance and galvanic response of skin respectively and the capacitive sensors for penetration depths of electromagnetic field in to the skin besides an optical sensor for blood flux measurement, finally the moments of the study objects are taken care by 3 axis accelerometer. the whole set up is shown in below fig.Results shown the decrease in conductance to the increase in glucose level, where the inverse of conductance is taken for impedance calculation [1].

Reference:
[1]M.S. Talary1, F. Dewarrat1, D. Huber1, L. Falco-Jonasson1 and A. Caduff1 Non-Invasive Impedance based Continuous Glucose Monitoring System, ICEBI 2007, IFMBE Proceedings Vol. 17.