Non-Invasive Target Detection Enhanced Through a Low-Frequency Passive Metasurface for Biomedical Applications

In this paper, an innovative biomedical system for magnetically-contrasted malignant inclusions detection, exploiting a low-frequency and passive metasurface, is presented. In particular, the proposed system, operating around 3 MHz, is composed by a passive metasurface inductively coupled to an external probe loop. The 5×5 metasurface, whose unit-cells consist in a 10-turn planar resonant spiral coil, globally covers a 21 cm × 21 cm area. The inclusion detection and localization are achieved by observing an external probe loop input impedance variations, enhanced by the interposed passive metasurface. By scanning through the probe loop the passive metasurface, placed 2 mm below the investigated tissue, a detection over the entire Field of View can be carried out. To validate the theorical approach, we performed preliminary full-wave simulations, obtaining promising results and demonstrating the possibility to detect and localize a 5 mm radius magnetic inclusion inside the investigated tissue, although the extremely low frequency adopted. Beside the good sensitivity, one of the most important advantages of the system is also the use of non-ionizing radiation, allowing to reduce the invasiveness for the patients. For this reason, the proposed solution can be considered as a non-invasive, low-frequency and contactless near-field biomedical system, encouraging future works.