STIMUSURE aimed to develop the first magnetoencephalography (MEG) sensor compatible with simultaneous transcranial magnetic stimulation (TMS). TMS is the most precise non-invasive brain stimulation method, and MEG is the most precise non-invasive brain recording technique. Combining the two would allow for more precise functional brain imaging and enable development of tools that would help us understand the functional connectivity between brain regions.
STIMUSURE developed an optically pumped magnetometer (OPM) sensor prototype for MEG. The developed sensor could both withstand TMS pulses (peak magnetic field 10,000 times the Earth’s magnetic field) and record weak magnetic brain magnetic fields (typical magnetic field less than 1/100,000,000 times the Earth's magnetic field, or about one trillionth of the peak field during TMS).
The project, however, could not reach the aim of recording MEG signal from the human brain shortly after TMS pulses as the residual magnetic fields of the TMS coil could not be reduced by the required factor of 1,000,000,000,000 sufficiently fast, taking over 0.05 s rather than the desired below 0.01 s to suppress the residual field after each TMS pulse. To solve this technical limitation would require development of better TMS hardware. The project did, however, result in the first intrinsic optically pumped magnetic gradiometer for human use.