Multisensor concept for non-invasive physiological monitoring

Numerous reports describe the use of non invasive glucose monitoring techniques, mostly in an in-vitro setting or under controlled in-vivo conditions [1], [2]. Impedance Spectroscopy (IS) is an example of such a technique that has been used to monitor changes in the glucose level caused by alterations in the electrolyte balance in skin and underlying tissue. The resulting changes in AC and DC conductivity can be analyzed using IS. However, it has been shown that additional external or physiological factors can also affect the measurement. In our previous work, various potentially perturbing parameters have been investigated, such as blood flux, the impact of environmental and body temperature changes and the effect of different arm positions [3], [4]. Here we report on two experimental clinical trials (part 1 and part 2) which were set up to further investigate these perturbations and parasitic effects (e.g. temperature, attachment, moisture and perfusion of blood in the tissue).