6.5-GHz Brain Stimulation System Using Enhanced Probe Focusing and Switch-Driven Modulation
This article, for the first time, presents the design, fabrication, and measurement results of a novel microwave brain stimulation system enabling efficient probe focusing of rectangular-pulse enveloped 6.5-GHz waves. While the conventional ON/OFF stimulation systems in literature employ low frequen...
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Published in | IEEE transactions on microwave theory and techniques Vol. 69; no. 9; pp. 4107 - 4117 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
New York
IEEE
01.09.2021
The Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
Subjects | |
Online Access | Get full text |
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Summary: | This article, for the first time, presents the design, fabrication, and measurement results of a novel microwave brain stimulation system enabling efficient probe focusing of rectangular-pulse enveloped 6.5-GHz waves. While the conventional ON/OFF stimulation systems in literature employ low frequencies below 0.5 GHz, the proposed system employs 6.5 GHz that can achieve more spatial energy focusing and a moderate level of energy penetration depth. In the proposed system, the ON/OFF modulated microwave signal is generated by a single chip consisting of a voltage-controlled oscillator (VCO) and power amplifier (PA). The VCO is driven by a switch at the current source to generate modulated signals with over 20-dB isolation between the high and low states. The probe with a center-opened aperture surrounded by a symmetric loading enables low power reflection toward the brain and focuses the field in the square-shaped aperture of 1-mm 2 area. Finally, it is demonstrated that the 20-min stimulation of an in vivo mouse brain using microwave signals with 1-Hz repetitive pulse envelopes and 1% duty cycle enables the normalized firing rate to reach up to 0.2 while the normalized firing rate stays just within ±0.05 under no stimulation. This suggests that the proposed brain stimulation system can achieve a dramatic change in the activity of individual hippocampal neurons. |
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ISSN: | 0018-9480 1557-9670 |
DOI: | 10.1109/TMTT.2021.3075726 |