Capacitive fringing field sensors in printed circuit board technology

Abstract

Capacitive fringing field sensors utilizing interdigitated electrode structures have been utilized in many applications. Printed circuit board technology is useful for realizing this type of sensor architecture by fabricating the interdigitated electrode structures in the patterned Cu foil. Furthermore, the solder mask coating is useful for insulating the electrodes to prevent shorting in the presence of water. Using this approach, prototype sensors were designed, simulated, fabricated and successfully evaluated. Applications include water detection and quantity measurement, and soil moisture content measurement.