Continuous measuremen...

It has been shown that in vivo glucose level changes affect the dielectric characteristics of the skin and underlying tissue, which can be measured non-invasively by impedance spectroscopy (IS). For a successful implementation of such an impedance sensor it is necessary that the sensor, when placed in contact with human skin, has a sufficient field penetration depth so that it is not only sensitive to changes in the dielectric properties of the upper skin layer, but also has a higher sensitivity to changes in the deeper skin layers. This is due to the fact that the upper layers of the skin are poorly vascularised, therefore their dielectric properties have a low sensitivity to changes associated with blood and intravascular fluids. A simplified model of the human skin and underlying tissue has been developed using electromagnetic field finite element simulations. This model can be used to optimise the electrode design of the impedance sensor. Initially, the applicability of the simulation concepts has been tested by comparing simulations with measurements of reference materials using sensor