Capacitive fringing field sensors in printed circuit board technology

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.

[1]  Ren C. Luo,et al.  Design and implementation of capacitive proximity sensor using microelectromechanical systems technology , 1998, IEEE Trans. Ind. Electron..

[2]  S. Aoyagi,et al.  Surface Micromachinable Accelerometer using Fringe Electrical Field of Penetrating Ferroelectric Substrate and its Characterization , 2007, TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference.

[3]  Hairudin Abdul Majid,et al.  A Capacitive Sensor Interface Circuit Based on Phase Differential Method , 2009 .

[4]  L. S. Riggs,et al.  Finite-element analysis of microstrip systems in the vicinity of a substrate edge and approximate formulas for capacitance , 1994 .

[5]  M. Casada,et al.  Fringing Field Capacitance Sensor for Measuring the Moisture Content of Agricultural Commodities , 2008, IEEE Sensors Journal.

[6]  Alanson P. Sample,et al.  A capacitive touch interface for passive RFID tags , 2009, 2009 IEEE International Conference on RFID.

[7]  Francis Menil,et al.  Influence of the electrodes configuration on a differential capacitive rain sensor performances , 2006 .

[8]  L. Byrd,et al.  Moisture content estimation in paper pulp using fringing field impedance spectroscopy , 2004, IEEE Sensors Journal.

[9]  K.R. Demarest,et al.  Engineering Electromagnetics , 1997, IEEE Electrical Insulation Magazine.

[10]  A. Caduff,et al.  Measurement and simulation of conductive dielectric two-layer materials with a multiple electrodes sensor , 2008, IEEE Transactions on Dielectrics and Electrical Insulation.