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 t he quality factor drops significantly. However, ongoing MRI experiments show promising results, leading to significant SNR enhancement in the region of interest.