Dual Mode Split Ring Resonator Sensing and Hyperthermia Array for Skin

Abstract

We demonstrate an applicator array based on split ring resonators (SRR) and microstrip coupled lines to serve as a dual-mode tool to conduct both microwave sensing and hyperthermia for skin cancer. The prototype applicator is realized on a low-cost, multi-layer substrate and designed to host 3 × 3 unit cells in which each unit in a row is tuned to a separate frequency ranging from 8 to 15 GHz (unloaded). E-field enhancement is achieved across the sensing regions between SRR loop terminals by feeding magnetically coupled energy to SRRs through microstrip transmission lines. The concentrated E-field leads to the applicator's high sensitivity that is also enhanced by the via fences surrounding the unit cells. EM simulation and equivalent circuit extraction are analyzed to ensure resonance consistency. We further observe the sensing capability on different skin-mimicking, off-the-shelf animal tissue in both simulations and experiments by distinguishing resonance shift and attenuation with different material under test (MUT). Coupled with transient infrared imaging, we further demonstrate hyperthermia capabilities of the applicator using skin-mimicking tissue. Using less than 5 W of input power, the applicator can induce therapeutic temperature elevation.