Bioelectric impedance analysis (BIA) is an established technique for measuring body composition, such as body fat and fat-free mass. The BIA method, however, depends sensitively on electrode placement, integrates the tissue impedance over a large volume of the body, andrequires a generic model of body composition for interpretation. A method based on electromagnetic induction is proposed for measuring the same tissue properties as BIA (both the resistive and reactive components of the tissue impedance at multiple frequencies), but with two crucial differences: the measurement is local (confined to a small region of the body below the sensor) and non-contact, which eliminates uncertainties related to the skin-electrode contact impedance and sensitivity to electrode placement. The frequency dependence of the resistive-reactive phase angle will be investigated as a robust means of identifying the tissue type. A sensor suitable for human subjects will be built, but used to study a variety of tissue samples in Phase I. The device will be evaluated on human subjects in Phase II.
Body composition analysis is of great interest to health professionals in assessing fityness and some diseases. A non-contact, local measurement of body composition would have significant commercial potential since it avoids several key problems associated with traditional bioelectric impedance analysis, which forms the basis of a large number of commercial devices for body composition measurement.
