2 research outputs found
Double-containment coil with enhanced winding mounting for transcranial magnetic stimulation with reduced acoustic noise
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 in a rigid block, which is mounted to the outer casing by its
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 sound is
absorbed by foam within the casing. The casing thickness under the winding
center is minimized to maximize the coil electric field output. Results:
Compared to commercial figure-of-eight TMS coils, the DCC prototype has 10-33
dB(Z) lower SPL at matched stimulation strength, whilst providing 22% higher
maximum stimulation strength than equally focal commercial 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.Comment: 8 pages, 5 figure