This paper proposes a new non-contact impedance imager based on phase differential technique enabling an enhanced detection of the existence of a tumor in tissues. The developed sensor is composed of an air supply system and two optical fiber based distance sensors next to the air nozzle. For a periodic air pressure, two distance sensors provide us with sinusoidal outputs with individual phases. The phase difference varies according to the change of impedance parameters of tissues between two points. A big advantage of the sensor is that the sensor can work irrespective of the color of tissues. Toward the implementation into human lung, the impedance parameters are measured for lung in vitro by using the developed sensor