Design and Analysis of Metasurfaces Comprising Dumbbell Shaped Cross-Grids for Magnetic Field Enhancement in MRI

Improving the signal-to-noise ratio (SNR) of magnetic resonance imaging (MRI) without boosting magnetic field strength is challenging due to the limitations of existing methods such as dielectric pads and bulky metamaterials. This work proposes a compact metasurface comprising bi-layers of dumbbell shaped cross-grids, separated by a flexible substrate, for 1.5T MRI. The design minimizes RF energy dissipation, enhances electromagnetic coupling, and achieves a magnetic field penetration depth of 80 mm, enabling deeper tissue imaging. Its symmetrical structure ensures uniform response in all orientations, making it direction-independent. Numerical simulations show superior SNR enhancement compared to prior designs. This advancement offers a practical and efficient solution for SNR improvement in clinical MRI.