Small Triple-Band Meandered PIFA for Brain-Implantable Biotelemetric Systems: Development and Testing in a Liquid Phantom

Abstract

We present a meandered triple-band planar-inverted-F antenna (PIFA) for integration into brain-implantable biotelemetric systems. The target applications are wireless data communication, far-field wireless power transfer, and switching control between sleep/wake-up mode at the Medical Device Radiocommunication Service (MedRadio) band (401–406 MHz) and Industrial, Scientific and Medical (ISM) bands (902–928 MHz and 2400–2483.5 MHz), respectively. By embedding meandered slots into the radiator and shorting it to the ground, we downsized the antenna to the volume of 11 × 20.5 × 1.8 mm3. We optimized the antenna using a 7-layer numerical human head model using full-wave electromagnetic field simulation. In the simulation, we placed the implant in the cerebrospinal fluid (CSF) at a depth of 13.25 mm from the body surface, which is deeper than in most works on implantable antennas. We manufactured and tested the antenna in a liquid phantom which we replicated in the simulator for further comparison. The measured gain of the antenna reached the state-of-the-art values of −43.6 dBi, −25.8 dBi, and −20.1 dBi at 402 MHz, 902 MHz, and 2400 MHz, respectively.

A Review of Miniaturized Advanced IC Rectenna for Energy Harvesting Applications

“…The meander structure is reported in [53] and developed by Nikta in 2021 [54], fractal geometries [55], Flower-shape radiating patch [56], Circular Maze shaped [57], and several geometries shaped radiator are suggested in [58] [59] [60] for energy harvesting applications. The materials with a high ε of substrate, loading, and resonance frequency are techniques used in implant antennas to achieve miniaturization.…”

A metamaterial unit-cell based patch radiator for brain-machine interface technology

“…Numerous endeavours have been made to design implantable antennas for brain applications [ [5] , [6] , [7] , [8] , [9] ]. For instance, a compact, circular-shaped brain implantable antenna with dimensions of 39.3 exhibited a bandwidth of 14.9% and a gain of −20.75 dBi at the 2.4 GHz frequency [ [ 5 ]].…”

“…The consequences of elevated temperatures within the human body include tissue damage, physical pain, etc. A meandered planar-inverted-F antenna (PIFA) with a total volume of 11 × 20.5 × 1.8 was proposed for triple-band operation (401–406 MHz, 902–928 MHz, and 2400–2483.5 MHz), exhibiting comparatively low gains of −43.6 dBi, −25.8 dBi, and −20.1 dBi, respectively [ [ 9 ]]. A homogeneous liquid phantom was used to measure the antenna, and the ISM band (2400 MHz) shifted to a slightly higher band in that test.…”

“…In contrast, a substrate of higher permittivity will affect radiation efficiency by converting antenna input power into surface waves [ [ 13 ]]. Techniques like incorporating shorting pins between the radiating patch and ground [ [ 4 ]] or lengthening current paths within the antenna radiator have been employed to minimize antenna size while maintaining optimal performance [ [ 9 , 11 ]]. Furthermore, compact-sized implantable antennas often exhibit limited bandwidth.…”

A Dual-Band Compact Integrated Rectenna for Implantable Medical Devices

“…Several structures of the implantable antennas design can be used to get miniaturization process such as serpentines [20], and spiral structure [21] is developed by Le Trong in 2021 [22] by using an open-ended slot at the ground for human head-implantable wireless communications utilizing a triple band antenna. Meander structure is reported in [23] and developed by Nikta in 2021 [24], fractal geometries [25], Flower-shape radiating patch [26], Circular Maze shaped [27], and several geometries shaped radiator are suggested in [28][29] [30] for energy harvesting applications. The materials with a high ε of substrate, loading, and resonance frequency are techniques used to achieve miniaturization.…”