Microcurrent electrical neuromuscular stimulator
A microcurrent electrical neuromuscular stimulator or MENS (also microamperage electrical neuromuscular stimulator) is a device used to send weak electrical signals into the body. Such devices apply extremely small (less than 1 microampere) electrical currents to nerves using electrodes placed on the skin. One microampere (uA) is 1 millionth of an ampere and the uses of MENS are distinct from those of "TENS" which runs at one milliamp(mA) or one thousandth of an amp.
https://en.wikipedia.org/wiki/Microcurrent_electrical_neuromuscular_stimulator