Determining the Relative Permittivity of Deep Embedded Biological Tissues

This letter introduces a novel in vivo method for determining the dielectric properties of deep human tissues, including lungs. A surgery-free method is proposed for an on-body monitoring system to evaluate the electrical properties of internal body organs and to detect irregularities in real time. The method uses a set of electrodes (16 or 40 MHz in operational frequency) to obtain data that relates the electrical properties of the underlying biological tissue(s) to the measured port scattering parameters. By using multiple electrodes, effects from outer layers (skin, fat, and muscle) can be suppressed, allowing for an accurate characterization of deeper layers. Specifically, the dielectric constant is expressed as a weighted sum of the scattering parameters from each probe. The weights of the scattering coefficients are then determined through a training process to ensure that various changes in the outer layers do not contaminate the extraction of the dielectric constant(s) associated with deeper tissues.