Micro current is current in millionths of an ampere. An ampere is a measure of the movement of electrons past a point. Microamperage current is the same kind of current your body produces on its own within each cell. This is current in millionths of an amp. It is very small; there is not enough current to stimulate sensory nerves so the current flow cannot be felt. You can tell it is running by watching the conductance meter on the machine.