Related Experiment Video
Updated: Jul 16, 2026
Electrode Positioning and Montage in Transcranial Direct Current Stimulation
Published on: May 23, 2011
Perception of comfort during transcranial DC stimulation: effect of NaCl solution concentration applied to sponge
J E Dundas1, G W Thickbroom, F L Mastaglia
1Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Australia. dundaj02@student.uwa.edu.au
Objective:
To investigate the relationship between perception of comfort and electrolyte concentration and applied voltage during transcranial direct current stimulation (tDCS).
Methods:
NaCl solutions (15, 140 and 220 mM NaCl) or deionised water were used as electrolytes to dampen tDCS sponge electrodes. Subjects (14, 7 M, 20-60 years of age) rated comfort on an 11-point scale during 2 min of tDCS (1 mA).
Results:
Overall participants rated tDCS as comfortable. Perception of comfort was negatively correlated with NaCl concentration (Spearman's rho=-0.88; p<0.05), and a logarithmic relationship was found between applied voltage and ionic strength of electrolytes (Pearson's r=-0.635; p<0.01). There was no relationship between applied voltage and perception of comfort.
Conclusions:
The application of NaCl solutions between 15 and 140 mM to sponge electrodes is more likely to be perceived as comfortable during tDCS.
Significance:
The reporting of solution concentration and ratings of perception would be useful adjuncts to tDCS studies.
