A Single-Layer Metasurface Resonator for 3T MRI Local Signal Enhancement

Metamaterials, in particular 2D metasurfaces, offer great potential to advance the measurement efficiency in Magnetic Resonance Imaging (MRI). The signal-to-noise ratio (SNR) can be improved significantly in a multifold of applications. One major drawback of MRI-compatible metamaterials usually is their bulky structure. This problem can be overcome by flat stripe-resonator metasurfaces. Here, we take the next step and investigate the use of interdigital capacitors (ID) to electrically elongate the wires composing a single-layer metasurface resonator. A comprehensive study of the fundamental mode, which is of particular interest for MRI, is presented. To that end, the on-bench performance of two prototypes are compared, one of which is designed with the help of structural parallel-plate (PP) capacitors on two layers, while the second one uses the interdigital, single-layer version. Although the adoption of interdigital capacitors simplifies prototyping, we observe that the quality factor drops significantly. However, ongoing MRI experiments show promising results, leading to significant SNR enhancement in the region of interest.