xTMS: A Pulse Generator for Exploring Transcranial Magnetic Stimulation Therapies

Area of Science:

• Biomedical Engineering
• Neuroscience
• Electrical Engineering

Background:

• Transcranial magnetic stimulation (TMS) requires precise control over stimulus pulse parameters.
• Existing TMS systems have limitations in flexibility and emulation capabilities.
• Advanced pulse generation is crucial for exploring novel TMS therapies.

Purpose of the Study:

• To introduce a highly flexible cascaded H-bridge based pulse generator for TMS.
• To demonstrate the system's capability to emulate existing commercial and research TMS devices.
• To present a superior control algorithm for TMS pulse generation.

Main Methods:

• Development of a cascaded H-bridge topology for pulse generation.
• Implementation of an offline model predictive control (MPC) algorithm for pulse sequencing.
• Design and construction of a laboratory prototype capable of high voltage and current output.

Main Results:

• The system provides complete flexibility in pulse shape, duration, direction, and repetition rate.
• The MPC algorithm demonstrated superior performance over conventional carrier-based pulse width modulation.
• The prototype successfully delivered pulses up to 1.5 kV and 6 kA.

Conclusions:

• The developed TMS pulse generator offers unprecedented flexibility and control.
• The MPC-based approach enhances TMS pulse generation precision and performance.
• The prototype serves as a valuable research tool for advancing TMS therapies.