Electrode design optimization of a CMOS fringing-field capacitive sensor

Li, Yuting; Tzeng, Y. L.; Chao, Chih-Ming; Wang, Kerwin

doi:10.1109/nems.2012.6196848

Cited by 1 publication

(1 citation statement)

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“…Many applications, however, utilize a planar electrode configuration where the electrodes are arrayed as parallel fingers on a nonconductive substrate [20][21][22]. Another electrode configuration for fringing field sensing is a two-dimensional array of metal electrode islands [23]. Rigid printed circuit board (PCB) technology has recently been demonstrated for realizing low-cost, small or large area, capacitive fringing field sensors where an FR-4 laminate was used as the rigid nonconductive substrate.…”

Section: A Capacitive Fringing Field Sensing Structuresmentioning

confidence: 99%

Capacitive Fringing Field Moisture Sensors Implemented in Flexible Printed Circuit Board Technology

Dean¹,

Hamilton²,

Baginski³

2014

Journal of Microelectronics and Electronic Packaging

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AbstractÀCapacitive fringing field sensors are often used in applications where moisture is detected, since the dielectric constant of liquid water is approximately 80 times greater than the dielectric constant of air. Most of these sensors, however, are realized using rigid substrates. Some applications would benefit from using a flexible capacitive fringing field sensor that could be conformally mounted on a nonplanar surface. Flexible printed circuit board technology is a mature commercially available process for manufacturing flexible electronics. This same technology can also be used to realize flexible fringing field moisture sensors where the patterned Cu foil is used for the electrodes and the soldermask coating electrically insulates the electrodes from being electrically shorted by moisture in the detection environment. Sensors were designed and characterized through flat and bending tests in air and in water. The tests demonstrated that bending a sensor over a radius of curvature as small as 13.7 mm had no measurable impact on sensor performance in air or in water. The sensors achieved a 3:1 increase in capacitance when immersed in water compared with in air.

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