Compact Quad-band Meandered Implantable PIFA for Wireless Brain Care

Abstract

In the growing efforts of promoting patients’ life quality through health technology solutions, implantable wireless biomedical telemetry systems have been identified as one of the frontrunners. In these systems, the design of implantable antennas is of prime importance in establishing the wireless data link. Small multitasking implantable antennas are an evolving wireless health technology for monitoring medical conditions. These implantable antennas are intended for different functions including wireless data transmission at Medical Device Radiocommunication Service (MedRadio) band (401-406 MHz) and Wireless Medical Telemetry Service (WMTS) bands (1395-1400, and 1427-1432), wireless power transfer, and control signals between sleep/wake-up modes at Industrial, Scientific, and Medical (ISM) bands (902-928 MHz and 2400-2483.5 MHz), respectively. In this paper, we present a meandered quad-band planar inverted-F antenna (PIFA) for wireless brain care. Employing the meandering miniaturizing technique, shorting the radiator to the ground plane, and high-permittivity substrate/superstrate layers (Rogers RO3210; $\varepsilon_{r}=10.2, \tan \delta=0.003, h=0.635 mm$) lead to downsizing the antenna volume greatly to $11 \times 20.5 \times 1.8 mm^{3}$ that includes the biocompatible silicone coating. We developed and characterized the proposed antenna numerically utilizing a 7-layer human head model in full-wave electromagnetic field simulation, where the antenna was implanted in the cerebrospinal fluid (CSF) layer at the depth of 13.25 mm in the cranial cavity. Overall, we achieve a compact quad-band implantable PIFA with -42.3 dBi of gain with a radiation efficiency of 0.003 % at 402 MHz, -22.7 dBi gain with a radiation efficiency of 0.1 % at 902 MHz,-23.7 dBi gain with a radiation efficiency of 0.1 % at 1430 MHz, and -29.7 dBi gain with a radiation efficiency of 0.02 % at 2450 MHz. To our knowledge, this is the first self-matched quad-band antenna proposed for wireless implant communications.