Fig. 1
From: Harnessing metamaterials for efficient wireless power transfer for implantable medical devices
a Classification of conventional material and four types of metamaterials in four different regions (ZIM: Zero Index Metamaterials), (b) Classification of common WPT methodologies which mostly focused on metamaterials, (c) Representation of a bio-implant WPT system including metamaterials where the electromagnetic wave is guiding the metamaterial for better PTE