Use the included USB charging cable connected to any USB power socket.
It looks a bit like vaseline but it's actually conductive paste. You put a little smudge on the gold electrodes of the clip before clipping the clip to your tragus.
The conductive paste greatly reduces the resistance between your skin and the electrical circuit.
The effect of using paste is to greatly reduce the sensation of the stimulation. In our tests users were able to stimulate at much higher levels without discomfort when using this conductive paste.
If you didn't find the answer to your tVNS question? Then please ask it here and we will endeavour to answer.