Patent ID: 7753846

Claim:
An apparatus of measuring skin moisture content, the apparatus comprising: an electrode unit comprising a reference (R) electrode, a current (C) electrode, and a measuring (M) electrode; an operational amplifier comprising an inverting input terminal that is supplied with a first voltage and connects with the R electrode, and an output terminal that connects with the C electrode; a switch to control a connection between the output terminal and the C electrode; and a comparison control unit to compare the first voltage and a voltage at the output terminal, and controlling the switch to connect the output terminal and the C electrode when the voltage at the output terminal is less than or equal to a value that is acquired by multiplying the first voltage and a predetermined constant, wherein the comparison control unit controls the switch to release the connection between the output terminal and the C electrode when the voltage at the output terminal is greater than the value that is acquired by multiplying the first voltage and the predetermined constant.