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Implanted miniaturized antenna for brain computer interface applications: analysis and design.

Zhao Y, Rennaker RL, Hutchens C, Ibrahim TS - PLoS ONE (2014)

Bottom Line: The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

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.

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Implanted antenna at three different locations inside the human head model.
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pone-0103945-g005: Implanted antenna at three different locations inside the human head model.

Mentions: The performance of the implanted antenna is influenced by all surrounding materials which includes the biocompatible insulating layers and the lossy human head tissues. In this section, the same rectangular antenna is simulated at three different locations inside the human brain model. For the clinical usage, the BCI devices are normally implanted between the dura and the grey matter [1]. Hence, the three different locations are all proposed around the dura which is responsible for keeping in the cerebrospinal fluid. In Figure 5, the dura is represented by the light orange color around the brain cortex. Above the dura is the cortical bone and below the dura are the combination tissues of the dura and grey matter in the head model. Their constitutive properties and the simulated antenna positions in this head model are listed in Table 1. The same insulating layer (thickness of 1 mm and relative permittivity of 2.1) is used for three different simulation cases.


Implanted miniaturized antenna for brain computer interface applications: analysis and design.

Zhao Y, Rennaker RL, Hutchens C, Ibrahim TS - PLoS ONE (2014)

Implanted antenna at three different locations inside the human head model.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4117534&req=5

pone-0103945-g005: Implanted antenna at three different locations inside the human head model.
Mentions: The performance of the implanted antenna is influenced by all surrounding materials which includes the biocompatible insulating layers and the lossy human head tissues. In this section, the same rectangular antenna is simulated at three different locations inside the human brain model. For the clinical usage, the BCI devices are normally implanted between the dura and the grey matter [1]. Hence, the three different locations are all proposed around the dura which is responsible for keeping in the cerebrospinal fluid. In Figure 5, the dura is represented by the light orange color around the brain cortex. Above the dura is the cortical bone and below the dura are the combination tissues of the dura and grey matter in the head model. Their constitutive properties and the simulated antenna positions in this head model are listed in Table 1. The same insulating layer (thickness of 1 mm and relative permittivity of 2.1) is used for three different simulation cases.

Bottom Line: The results show that thin (on the order of 100 micrometers thickness) biocompatible insulating layers can significantly impact the antenna performance.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.

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.

Show MeSH
Related in: MedlinePlus