Integrated relative humidity sensor

Abstract

The sensor described combines a polymer-based capacitive humidity sensor on the same chip with CMOS electronics. The resulting three-lead integrated sensor provides a DC output voltage which varies linearly with relative humidity. Thus, the sensor is readily adapted to conventional 4-20-mA control loops. Its low power consumption ( approximately 1 mW at 5 V) makes it useful for battery operation and the DC output eliminates the need for shielded cable and special connectors in applications requiring the sensor to be located remote from auxiliary electronics.< >