Effect of Electrode Size and Maximum Current Limitation on Multichannel Transcranial Electrical Stimulation Optimization

Transcranial electrical stimulation (tES) is a promising non-invasive brain modulation technique in clinical application. Optimization methods have been used to provide optimal stimulus patterns to improve focality and intensity at target based on accurate individual head model, but most of tES optimization approaches were implemented using the same small size electrode. There is a lack of relevant research that investigate the effect of electrode size and maximum current limitation on tES optimization. The purpose of this study is to evaluate the optimization performance using multi-size electrode and different maximum current limitations at each electrode. By quantitatively comparing distribution changes of electric field and optimal current, it was found that electrode size has no significant effect on stimulation optimization within certain range. More focal fields and fewer active electrodes were observed when the maximum per electrode current limitation increases. It suggests that tolerance and operability of tES could improve when the maximum current limitation for per electrode and electrode size increases synchronously.