Thin film based flexible current clamp sensor for green wireless sensor networks

This paper presents a novel film based flexible clamp type current sensor for green wireless sensor networks fabricated by printed silver paste coil using the process technology in screen-printing as a low cost, simple, and rapid method. Since developed sensor has high flexibility, it can be used by winding the cable and drastically reduce the installation space. In addition, it can construct wireless sensor networks easily because wireless terminals can drive autonomously without external power supply by utilizing the secondary current generated in the coil of the sensor by electromagnetic induction. The sensor´s output voltage changed linearly with variation of the value of primary current in the 0 to 100 A range. When the value of primary current was 100 A, the output voltage was 69 mV per 150 turns in the coil. Although the ambient temperature around the sensor was raised at 80 °C due to heat evolved by the electric resistance of the coil, there was no almost variation of the voltage. This result indicates the practical applicability as the current sensor for electrical cables.