Complementary Split-Ring Resonators for Non-Invasive Characterization of Biological Tissues

Planar microwave sensors are very interesting for health applications, such as the investigation of dielectric properties of biological tissues in a non-invasive and contactless manner. In this paper, three structures of complementary split-ring resonators (CSRRs) coupled to microstrip lines are investigated with ex-vivo characterization of animal tissues. Compared to ring resonators, their main advantage consists in more compact sensors, enabling a better local dielectric characterization of the tissues. The extraction of dielectric parameters is obtained by an optimization process based on a comparison of experimental results with electromagnetic simulations with full-wave three-dimensional (3D) finite element method implemented in HFSS and CST.