Modular multilevel TMS device with wide output range and ultrabrief pulse capability for sound reduction

Area of Science:

• Neuroscience
• Biomedical Engineering
• Electrical Engineering

Background:

• Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique.
• Existing TMS devices have limitations in controlling pulse characteristics.
• Novel pulse generation is needed for advanced TMS applications.

Purpose of the Study:

• To present a novel modular multilevel TMS (MM-TMS) pulse generator.
• To demonstrate the device's capability for generating a wide range of pulse shapes, amplitudes, and widths.
• To explore the potential for novel TMS protocols and quieter stimulation.

Main Methods:

• Development of a MM-TMS device using ten cascaded H-bridge modules.
• Implementation with insulated-gate bipolar transistors for high-amplitude, ultrabrief pulses.
• Capability to generate up to 21 voltage levels and charge modules with a conventional TMS power supply.

Main Results:

• The MM-TMS device achieved peak coil voltages of 11 kV and currents of 10 kA.
• Enabled suprathreshold ultrabrief pulses and various complex waveforms (monophasic, biphasic, polyphasic, amplitude-modulated).
• Demonstrated reduced acoustic emissions with briefer pulses and enabled rapid, variable pulse sequencing.

Conclusions:

• The MM-TMS device offers unprecedented control over pulse characteristics.
• This enhanced control facilitates the development of novel TMS protocols.
• The technology holds promise for quieter and more versatile brain stimulation.