Optimized Metasurface Matching Layer for Biomedical Applications in Near Field [Electromagnetic Metamaterials]

Electromagnetic (EM) fields are widely used in several applications where maximizing penetration into the target object is desirable, such as biomedical imaging and sensing. This improvement is often achieved through a matching layer (ML), which can be either a dielectric material or dielectrics patterned with metallic structures. A metasurface ML (MML) represents an improvement over traditional dielectric MLs (DMLs) since it provides better impedance matching, leading to increased field strength within the target and reduced ML thickness. However, designing a MML for near-field EM sources has traditionally relied on time-consuming full-wave simulations. This article introduces a novel analytical approach to designing an MML for arbitrary near-field EM sources, providing a more efficient and effective solution. Three cases are analyzed to assess the reliability of the proposed approach: a short dipole, a small loop, and a patch antenna. The performance of the MML, obtained by an analytical procedure, is preliminarily assessed with full-wave simulations and then experimentally validated. The optimized MML is fabricated using 3D and 2D additive manufacturing (AM) techniques. A comparative analysis across all the considered scenarios confirms the robustness and reliability of the proposed MML design strategy.