Double-containment coil with enhanced winding mounting for transcranial magnetic stimulation with reduced acoustic noise

Lari M. Koponen; Stefan M. Goetz; Angel V. Peterchev

doi:10.1109/TBME.2020.3048321

Double-containment coil with enhanced winding mounting for transcranial magnetic stimulation with reduced acoustic noise

Lari M. Koponen, Stefan M. Goetz, Angel V. Peterchev^*

^*Corresponding author for this work

Psychology

Research output: Contribution to journal › Article › peer-review

4 Citations (Scopus)

88 Downloads (Pure)

Abstract

Objective: This work aims to reduce the acoustic noise level of transcranial magnetic stimulation (TMS) coils. TMS requires high currents (several thousand amperes) to be pulsed through the coil, which generates a loud acoustic impulse whose peak sound pressure level (SPL) can exceed 130 dB(Z). This sound poses a risk to hearing and elicits unwanted neural activation of auditory brain circuits.

Methods: We propose a new double-containment coil with enhanced winding mounting (DCC), which utilizes acoustic impedance mismatch to contain and dissipate the impulsive sound within an air-tight outer casing. The coil winding is potted into a rigid block, which is mounted to the outer casing through the blocḱs acoustic nodes that are subject to minimum vibration during the pulse. The rest of the winding block is isolated from the casing by an air gap, and the sound is absorbed by polyester fiber panels within the casing. The casing thickness under the winding center is minimized to maximize the electric field output.

Results: Compared to commercial figure-of-eight TMS coils, the DCC prototype has 18-41 dB(Z) lower peak SPL at matched stimulation strength, whilst providing 28% higher maximum stimulation strength than equally focal coils.

Conclusion: The DCC design greatly reduces the acoustic noise of TMS while increasing the achievable stimulation strength. Significance: The acoustic noise reduction from our coil design is comparable to that provided by typical hearing protection devices. This coil design approach can enhance hearing safety and reduce auditory co-activations in the brain and other detrimental effects of TMS sound.

Original language	English
Article number	9311190
Pages (from-to)	2233-2240
Number of pages	8
Journal	IEEE Transactions on Biomedical Engineering
Volume	68
Issue number	7
Early online date	30 Dec 2020
DOIs	https://doi.org/10.1109/TBME.2020.3048321
Publication status	Published - Jul 2021

Bibliographical note

Funding Information:
L. M. Koponen, S. M. Goetz, and A. V. Peterchev are inventors on patents and patent applications on TMS technology including the quiet TMS coil technology described in this paper. Related to TMS technology, S. M. Goetz has received research funding from Magstim, and A. V. Peterchev has received research funding, travel support, patent royalties, consulting fees, equipment loans, hardware donations, and/or patent application support from Rogue Research, Tal Medical/Neurex, Magstim, MagVenture, Neuronetics, BTL Industries, and ACI.

Manuscript received July 2, 2020; revised October 20, 2020 and December 6, 2020; accepted December 22, 2020. Date of publication December 30, 2020; date of current version June 18, 2021. Research reported in this publication was supported by the National Institute of Mental Health of the National Institutes of Health under Award Number R01MH111865 as well as by hardware donations from Magstim. (Correspondence author: Angel V. Peterchev.) Lari M. Koponen is with the Department of Psychiatry and Behavioral Sciences, Duke University.

Publisher Copyright:
© 1964-2012 IEEE.

Keywords

acoustic noise
coil design
optimization
TMS
Transcranial magnetic stimulation

ASJC Scopus subject areas

Biomedical Engineering

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10.1109/TBME.2020.3048321Licence: None: All rights reserved

KoponenL2020Double
L. M. Koponen, S. M. Goetz and A. V. Peterchev, "Double-Containment Coil With Enhanced Winding Mounting for Transcranial Magnetic Stimulation With Reduced Acoustic Noise," in IEEE Transactions on Biomedical Engineering, vol. 68, no. 7, pp. 2233-2240, July 2021, doi: 10.1109/TBME.2020.3048321. © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Accepted author manuscript, 1.31 MBLicence: Other (please specify with Rights Statement)

Cite this

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abstract = "Objective: This work aims to reduce the acoustic noise level of transcranial magnetic stimulation (TMS) coils. TMS requires high currents (several thousand amperes) to be pulsed through the coil, which generates a loud acoustic impulse whose peak sound pressure level (SPL) can exceed 130 dB(Z). This sound poses a risk to hearing and elicits unwanted neural activation of auditory brain circuits. Methods: We propose a new double-containment coil with enhanced winding mounting (DCC), which utilizes acoustic impedance mismatch to contain and dissipate the impulsive sound within an air-tight outer casing. The coil winding is potted into a rigid block, which is mounted to the outer casing through the blocḱs acoustic nodes that are subject to minimum vibration during the pulse. The rest of the winding block is isolated from the casing by an air gap, and the sound is absorbed by polyester fiber panels within the casing. The casing thickness under the winding center is minimized to maximize the electric field output. Results: Compared to commercial figure-of-eight TMS coils, the DCC prototype has 18-41 dB(Z) lower peak SPL at matched stimulation strength, whilst providing 28% higher maximum stimulation strength than equally focal coils. Conclusion: The DCC design greatly reduces the acoustic noise of TMS while increasing the achievable stimulation strength. Significance: The acoustic noise reduction from our coil design is comparable to that provided by typical hearing protection devices. This coil design approach can enhance hearing safety and reduce auditory co-activations in the brain and other detrimental effects of TMS sound.",

keywords = "acoustic noise, coil design, optimization, TMS, Transcranial magnetic stimulation",

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note = "Funding Information: L. M. Koponen, S. M. Goetz, and A. V. Peterchev are inventors on patents and patent applications on TMS technology including the quiet TMS coil technology described in this paper. Related to TMS technology, S. M. Goetz has received research funding from Magstim, and A. V. Peterchev has received research funding, travel support, patent royalties, consulting fees, equipment loans, hardware donations, and/or patent application support from Rogue Research, Tal Medical/Neurex, Magstim, MagVenture, Neuronetics, BTL Industries, and ACI. Manuscript received July 2, 2020; revised October 20, 2020 and December 6, 2020; accepted December 22, 2020. Date of publication December 30, 2020; date of current version June 18, 2021. Research reported in this publication was supported by the National Institute of Mental Health of the National Institutes of Health under Award Number R01MH111865 as well as by hardware donations from Magstim. (Correspondence author: Angel V. Peterchev.) Lari M. Koponen is with the Department of Psychiatry and Behavioral Sciences, Duke University. Publisher Copyright: {\textcopyright} 1964-2012 IEEE.",

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Double-containment coil with enhanced winding mounting for transcranial magnetic stimulation with reduced acoustic noise

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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