Wireless induction coils embedded in diamond for power transfer in medical implants
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Date
2017-08
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Wireless power and data transfer to medical implants is a research area where improvements in current state-of-the-art technologies are needed owing to the continuing efforts for miniaturization. At present, lithographical patterning of evaporated metals is widely used for miniature coil fabrication. This method produces coils that are limited to low micron or nanometer thicknesses leading to high impedance values and thus limiting their potential quality. In the present work we describe a novel technique, whereby trenches were milled into a diamond substrate and filled with silver active braze alloy, enabling the manufacture of small, high cross-section, low impedance microcoils capable of transferring up to 10 mW of power up to a distance of 6 mm. As a substitute for a metallic braze line used for hermetic sealing, a continuous metal loop when placed parallel and close to the coil surface reduced power transfer efficiency by 43%, but not significantly, when placed perpendicular to the microcoil surface. Encapsulation of the coil by growth of a further layer of diamond reduced the quality factor by an average of 38%, which can be largely avoided by prior oxygen plasma treatment. Furthermore, an accelerated ageing test after encapsulation showed that these coils are long lasting. Our results thus collectively highlight the feasibility of fabricating a high-cross section, biocompatible and long lasting miniaturized microcoil that could be used in either a neural recording or neuromuscular stimulation device.
Description
Keywords
Medical implant, Wireless power, Diamond, Braze, Silver ABA, Induction coil
Citation
Sikder, M. K. U., J. Fallon, M. N. Shivdasani, K. Ganesan, P. Seligman, and D. J. Garrett. 2017. Wireless induction coils embedded in diamond for power transfer in medical implants. Biomedical microdevices. 19(4): 79.