Galvanic Cell Sensor is designed for detecting reactive current. This current is the result of utilizing oxygen as an active material for a cell having a diaphragm, Pt-Pb electrodes, and electrolytic solution. This sensor is designed in durable and sturdy design that needs no external power supply. It is easy to install and use sensor available with wide marketability. In addition to this, result is relative to oxygen concentration linear up to 40vol%.