scispace - formally typeset
Search or ask a question
Author

Douglas C. Galbraith

Bio: Douglas C. Galbraith is an academic researcher. The author has contributed to research in topics: Data link & Circuit design. The author has an hindex of 2, co-authored 2 publications receiving 482 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: A detailed theoretical analysis of misalignment effects in RF coil systems, including lateral and angular misalignments, is presented.
Abstract: Radio-frequency (RF) coils are used extensively in the design of implantable devices for transdermal power and data transmission. The practical issues of coil misalignments and configurations have not been investigated, and this paper presents a detailed theoretical analysis of misalignment effects in RF coil systems, including lateral and angular misalignments. Formulas are derived for the mutual inductance and, whenever possible, simplified upper bounds and lower bounds of the coupling coefficient are provided. A design procedure is established to maximize coil coupling for a given configuration, and a companion paper [1] discusses a circuit design technique to reduce the effects of misalignment on transmission efficiency.

263 citations

Journal ArticleDOI
TL;DR: A new method of desensitizing the gain of an inductive link to the mutual coupling of its inductors when the coupling varies due to geometrical misalignments is described.
Abstract: This paper describes a new method of desensitizing the gain of an inductive link to the mutual coupling of its inductors. When the coupling varies due to geometrical misalignments [1] this design method guarantees good efficiency and a large bandwidth. The mathematics for four link combinations are presented, and examples of the link efficiency and bandwidth for one of the combinations are shown and discussed.

235 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: This work has analyzed the four-coil energy transfer systems and outlined the effect of design parameters on power-transfer efficiency, and a proof-of-concept prototype system is implemented and confirms the validity of the proposed analysis and design techniques.
Abstract: Resonance-based wireless power delivery is an efficient technique to transfer power over a relatively long distance. This technique typically uses four coils as opposed to two coils used in conventional inductive links. In the four-coil system, the adverse effects of a low coupling coefficient between primary and secondary coils are compensated by using high-quality (Q) factor coils, and the efficiency of the system is improved. Unlike its two-coil counterpart, the efficiency profile of the power transfer is not a monotonically decreasing function of the operating distance and is less sensitive to changes in the distance between the primary and secondary coils. A four-coil energy transfer system can be optimized to provide maximum efficiency at a given operating distance. We have analyzed the four-coil energy transfer systems and outlined the effect of design parameters on power-transfer efficiency. Design steps to obtain the efficient power-transfer system are presented and a design example is provided. A proof-of-concept prototype system is implemented and confirms the validity of the proposed analysis and design techniques. In the prototype system, for a power-link frequency of 700 kHz and a coil distance range of 10 to 20 mm, using a 22-mm diameter implantable coil resonance-based system shows a power-transfer efficiency of more than 80% with an enhanced operating range compared to ~40% efficiency achieved by a conventional two-coil system.

894 citations

Journal ArticleDOI
08 Nov 2004
TL;DR: This paper describes the development of a high-density electronic interface to the central nervous system that permits the long-term monitoring of neural activity in vivo as well as the insertion of electronic signals into neural networks at the cellular level.
Abstract: This paper describes the development of a high-density electronic interface to the central nervous system. Silicon micromachined electrode arrays now permit the long-term monitoring of neural activity in vivo as well as the insertion of electronic signals into neural networks at the cellular level. Efforts to understand and engineer the biology of the implant/tissue interface are also underway. These electrode arrays are facilitating significant advances in our understanding of the nervous system, and merged with on-chip circuitry, signal processing, microfluidics, and wireless interfaces, they are forming the basis for a family of neural prostheses for the possible treatment of disorders such as blindness, deafness, paralysis, severe epilepsy, and Parkinson's disease.

677 citations

Journal ArticleDOI
TL;DR: This work outlined the theoretical foundation of optimal power transmission efficiency in an inductive link, and combined it with semi-empirical models to predict parasitic components in PSCs to devise an iterative PSC design methodology that starts with a set of realistic design constraints and ends with the optimal PSC pair geometries.
Abstract: The next generation of implantable high-power neuroprosthetic devices such as visual prostheses and brain computer interfaces are going to be powered by transcutaneous inductive power links formed between a pair of printed spiral coils (PSC) that are batch-fabricated using micromachining technology. Optimizing the power efficiency of the wireless link is imperative to minimize the size of the external energy source, heating dissipation in the tissue, and interference with other devices. Previous design methodologies for coils made of 1-D filaments are not comprehensive and accurate enough to consider all geometrical aspects of PSCs with planar 3-D conductors as well as design constraints imposed by implantable device application and fabrication technology. We have outlined the theoretical foundation of optimal power transmission efficiency in an inductive link, and combined it with semi-empirical models to predict parasitic components in PSCs. We have used this foundation to devise an iterative PSC design methodology that starts with a set of realistic design constraints and ends with the optimal PSC pair geometries. We have executed this procedure on two design examples at 1 and 5 MHz achieving power transmission efficiencies of 41.2% and 85.8%, respectively, at 10-mm spacing. All results are verified with simulations using a commercial field solver (HFSS) as well as measurements using PSCs fabricated on printed circuit boards.

616 citations

01 Jan 1996
TL;DR: In this paper, a geometric approach for the enhancement of the coupling coefficient between two magnetically coupled coils is presented, where the turns of the coils are not concentrated at the Circumferences, but distributed across the diameters.
Abstract: This paper presents a geometric approach for the enhancement of the coupling coefficient between two magnetically coupled coils. It is demonstrated that the coupling coefficient can be considerably enhanced, if the turns of the coils are not concentrated at the Circumferences, but distributed across the diameters. For analysis, each of the two coils is assumed to be composed of concentric circular loops. The experimental results are in very good agreement with the theoretical results.

401 citations

Journal ArticleDOI
TL;DR: It is demonstrated that the coupling coefficient can be considerably enhanced, if the turns of the coils are not concentrated at the circumferences, but distributed across the diameters.
Abstract: This paper presents a geometric approach for the enhancement of the coupling coefficient between two magnetically coupled coils. It is demonstrated that the coupling coefficient can be considerably enhanced, if the turns of the coils are not concentrated at the circumferences, but distributed across the diameters. For analysis, each of the two coils is assumed to be composed of concentric circular loops. The experimental results are in very good agreement with the theoretical results.

401 citations