Electrovibration, cutaneous sensation of microampere current

The human threshold of sensation of 50 Hz current has hitherto been considered to be around 1 mA. A new sensing mechanism is reported which lowers the threshold about 3 decades. It is elicited when the skin slides on the current carrying conductor, and the sensation disappears when the skin is wet. The sensation is a feeling of vibration or increased surface roughness. The sensing mechanism has been shown to be due to electrostatic forces in the skin caused by the electric field in a poorly conducting stratum corneum. The mechanism is primarily potential dependent, and the absolute threshold of sensation has been found to be about 1.5 volt or 0.15 μA rms at 50 Hz. In practical daily‐life situations it is shown that 82% of 40 test subjects were able to sense a current of 2 μA rms, 50 Hz.