Design of On-Body Epidermal Antenna on AMC Substrate for UHF RFID in Healthcare

This article presents a compact AMC structure used as a shielding element for a generic wearable RFID tag at UHF frequencies for on-body applications, with an overall footprint limited to an area of only lambda(2)(0) (41.4 x 82.8 mm). Thanks to the isolation provided by the AMC planar structure, the tag antenna gain and reading range are increased by about one order of magnitude in comparison with the case of a conventional tag attached to the human body. The designed antenna is platform tolerant, with very good robustness and isolation with respect to the human body, exhibiting a high reliability. The AMC structure is implemented on a thin, flexible, and biocompatible high permittivity silicon-doped dielectric substrate, with apertures both in the substrate and in the ground plane to allow skin transpiration. Therefore, the presented device can be effectively used also as an epidermal antenna, allowing the "on-skin" sampling of the most typical health parameters. The presented configuration has been designed using CST Studio Suite. A prototype has been fabricated and fully characterized, and measured results are in very good agreement with simulations.