A device with controllable switch terminal voltage, comprising: a switch signal unit for outputting a corresponding switch signal according to the state of a switch, wherein the switch is coupled between the switch signal unit and an output of a power supply; a biasing unit coupled to the switch signal unit for outputting a bias voltage to the switch signal unit; wherein when the switch is open and a conductive liquid and/or the stream of conductive liquid exists inside the switch, the biasing unit cooperates with the switch signal unit so as to control the terminal voltage of the switch and the current flowing through the switch. The disclosed switch design allows the switch terminal voltage to be less than 1V when the switch is opened, which greatly depresses the electrochemical reaction of the switch, thus prolonging the switch life, and avoiding the possibility of hydrogen explosion.