Advisor(s)

Nian Sun

Contributor(s)

Bryan McLaughlin, Marvin Onabajo

Date of Award

7-2012

Date Accepted

7-2012

Degree Grantor

Northeastern University

Degree Level

M.S.

Degree Name

Master of Science

Department or Academic Unit

College of Engineering. Department of Electrical and Computer Engineering.

Keywords

EEG, Implant, Inductive Power, Wireless Power

Disciplines

Biomedical devices and instrumentation | Electrical and Computer Engineering | Engineering

Abstract

This thesis presents an implantable EEG recording system which was designed and constructed from discrete components. The implanted device has a novel form factor which utilizes flexible circuit materials to provide a versatile, minimally invasive platform for long term ambulatory EEG recording. Power and telemetry are provided through inductive coupling between the implant and external reader. Resonance is used to create an efficient inductive link capable of operating at a coil separation of up to several centimeters with load-impedance modulation of the data onto the resonant frequency carrier. In this work an alternative architecture is also considered with separate inductively coupled channels, one optimized for efficient power transfer and one optimized for efficient data transfer. In particular a thorough analysis of the theory of efficient power transfer is developed for the special case of a resonant inductively coupled link feeding into an efficient switching voltage regulator on the implant. Although various inefficient methods of regulating the supply voltage on the implant have been demonstrated in the literature, there is a lack of designs which implement a more efficient switching voltage regulator. In this analysis it is shown that without an efficient voltage converter on the implant side of the power link it is impossible to build a power link that operates at peak efficiency over a variable range of inductive coupling conditions. It is also demonstrated that active control of the source amplitude is necessary to maintain peak efficiency across the link. A complete inductive link optimized for power efficiency is developed and used to validate the theory using a constant power load circuit to emulate a switching regulator load. Finally a design process for creating a power efficient inductive link given an arbitrary set of operating requirements is outlined.

Document Type

Master's Thesis

Rights Holder

Andrew E. Czarnecki


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