Hermetic Implantable Antenna Inside Vitreous Humor Simulating Fluid

Abstract

Abstract-Retinal prosthesis system is currently being developed in various places around the world. This system involved data transfer between an implanted antenna inside an eyeball and an external camera that is located just in front of the eyeball. While there are plenty of publications about the stimulating electrodes or the processing unit of the system itself, very limited amount has been published regarding the wireless communication link between the two antennas despite the fact that the electromagnetic wave will propagate through a complex medium in the form of Vitreous Humor. This paper will discuss about the constraints associated with implanting an antenna into an eyeball. An antenna design and simulation was performed with the aid of High Frequency Structure Simulator (HFSS) and its Finite Element Method (FEM) mathematical solver in the operating frequency of 402-405 MHz. The antenna, which was a 4 layer microstrip antenna, was positioned at the centre of a spherical model filled with homogeneous Vitreous Humor material. Antenna performances that include return loss, bandwidth, gain, radiation pattern, and SAR value are analysed and compared against those of other implantable antennas operating in Medical Implant Communication Service (MICS) band. Free space and simulating fluid measurements were also conducted on the fabricated antenna to validate the simulation results. It was concluded that the fabricated antenna was able to produce the similar performance to the simulation results and hence at the same level as the other antennas operating in material with lower dielectric constants and conductivities.

Circularly polarized implantable antenna characterization for retinal prosthesis systems

“…In accordance, the PDMS superstrate material is used for all simulation analysis. It was shown in [12] that increments in superstrate thickness would result in better S 11 characteristics. Figure 7 depicts the simulation analysis for the proposed antenna with different superstrate thicknesses over the ISM bandwidth in order to achieve acceptable AR values.…”

Design of a Novel Compact MICS Band PIFA Antenna for Implantable Biotelemetry Applications

“…The proposed antenna inserted a shorting pin between the ground and the middle layer to increase the effective size of the antenna [ 12 ]. We introduced two cutting slots on the middle and top layer patches to extend the current path on radiation patches [ 13 , 14 ], thereby tuning the resonant frequency. These slots resulted in spiral rectangular-shaped strips for both layers.…”

Design of a miniaturised broadband 3 × 3 mm antenna for intraocular retinal prosthesis application

“…In [4], 7 × 7 mm sized intraocular microstrip antenna had been designed which is less efficient due to low return loss values. In [5], 10 × 10 × 2.54 mm sized four‐stacked layer microstrip intraocular antenna had been designed whose fabrication is so complex due to the use of multilayers and shorting pins rendering it unfit to be intraocular. It is to be noted that the above‐mentioned designs have serious limitations of low gain and narrow bandwidth that leaves no room for the extension of electrode capacity to enhance the image perception capability.…”