Implanted Miniaturized Antenna for Brain Computer Interface Applications: Analysis and Design

Abstract

Implantable Brain Computer Interfaces (BCIs) are designed to provide real-time control signals for prosthetic devices, study brain function, and/or restore sensory information lost as a result of injury or disease. Using Radio Frequency (RF) to wirelessly power a BCI could widely extend the number of applications and increase chronic in-vivo viability. However, due to the limited size and the electromagnetic loss of human brain tissues, implanted miniaturized antennas suffer low radiation efficiency. This work presents simulations, analysis and designs of implanted antennas for a wireless implantable RF-powered brain computer interface application. The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance. The proper selection of the dielectric properties of the biocompatible insulating layers and the implantation position inside human brain tissues can facilitate efficient RF power reception by the implanted antenna. While the results show that the effects of the human head shape on implanted antenna performance is somewhat negligible, the constitutive properties of the brain tissues surrounding the implanted antenna can significantly impact the electrical characteristics (input impedance, and operational frequency) of the implanted antenna. Three miniaturized antenna designs are simulated and demonstrate that maximum RF power of up to 1.8 milli-Watts can be received at 2 GHz when the antenna implanted around the dura, without violating the Specific Absorption Rate (SAR) limits.

Design and Characterization of a Miniaturized Implantable Antenna in a Seven-Layer Brain Phantom

“…Brain implant devices are designed to help both patients living with brain diseases and people with perspective neurological disorders during therapy and early diagnosis, respectively. For example, some applications of the brain implant technology include restoring lost sensory information from a disease [1] and early detection of epileptic seizures [2]. However, brain implant devices typically use wires to connect with external units that can threaten safety of the patients and limit their movements [2], [3].…”

A Miniature Implanted Antenna for Uhf Rfid Applications

“…This simulation aims at characterizing the thermal elevation in biological media exposed to electromagnetic waves. Indeed, the simulated results denote that the SAR10-g maximum value observed at 868 MHz is 1.31 W/kg (in the case of a Silicone thickness of 0.25 mm and a maximum supply power of 500 mW) which corresponds to the maximum allowed standard guideline in Europe (2 W/kg averaged over 10-g of tissue) [40,41]. Figure 22 shows the simulated 10-g average SAR maximum values at 868 MHz as a function of the insulation layer thickness by using CST software which gives us more options for simulating this parameter.…”

Wireless interrogation of small animal phantoms with a miniature implanted UHF RFID tag

“…2) is π x 13.5 2 x 70 mm 3 , with ε req = 40, tanδ eq = 0.39 and σ eq = 0.79 (S/m), being respectively the equivalent relative permittivity, the dielectric loss tangent and the conductivity, taking into account the different layers of the animal body. The total antenna volume is 30.5 mm 3 , which is very small compared to other structures operating in the same frequency band [8], [9]. In Fig.…”