A universal high-sensitivity area-variation capacitive displacement transducer (CDT) based on fringe effect

TY - JOUR

T1 - A universal high-sensitivity area-variation capacitive displacement transducer (CDT) based on fringe effect

AU - Wang, Qiu

AU - Yan, Shitao

AU - Xu, Qiangwei

AU - Zhang, Shaolin

AU - Song, Xiaoxiao

AU - Zhao, Chun

AU - Hu, Fangjing

AU - Liu, Huafeng

AU - Tu, Liangcheng

N1 - Funding Information: This work was supported in part by the Natural Science Foundation of Hubei Province under Grant 2019CFB108, in part by the Pre-Research Field Foundation of Equipment Development Department of China under Grant 61405170105, in part by the CAST-BISEE Innovation Funds under Grant CAST-BISEE2017-019, in part by the National Key Research and Development Program of China under Grant 2018YFC0603301 and Grant 2017YFC0601603, in part by the Natural Science Foundation of China under Grant 61306095 and Grant 61574067, and in part by the HUST Key Innovation Team Foundation for Interdisciplinary Promotion under Grant 2016JCTD102. Publisher Copyright: © 2019 IEEE.

PY - 2019/10/17

Y1 - 2019/10/17

N2 - Capacitive displacement transducers (CDTs) have been widely used in many physical sensors, attributing to high-resolution, simple electricity and easy manufacturing process. Gap-variation CDTs generally have higher displacement resolution due to small electrode gaps but suffer from the pull-in effect, the nonlinear effect and squeeze-film damping; whereas area-variation CDTs have intrinsically good linearity and much smaller slide-film damping. However, the parallel-plate-based area-variation CDTs have the electrode width much larger than the electrode gap with negligible fringe effect; therefore, the sensitivity is limited by periodic electrode numbers. In this paper, we introduce a novel fringe-effect dominated area-variation CDT with a much higher sensitivity within a certain electrode-deployable area. Both theoretical and numerical analysis are applied to investigate the working principle of the CDT design. The proposed fringe-effect-based CDT benefits from a much larger capacitance-to-displacement sensitivity than the traditional periodic array parallel-plate-based CDT, due to the more displacement-sensitive fringe field and more deployable electrode periods. A set of experiments are designed, and the proposed area-variation CDTs are evaluated. Experimental results suggested that the proposed CDT design, which had equal electrode width, separation and gap, could universally be applied to sensors with different featured dimensions either in macroscale or microscale. Angular misalignments with both out-of-plane tilts and in-plane rotations, which affect the output offset and sensitivity, should be minimized or alleviated. The proposed fringe-effect-based CDT are successfully applied to a single-axis in-plane sensing micro-electromechanical systems (MEMS) accelerometer, showing a noise floor as low as 0.25 ng/Hz1/2 @1 Hz. The corresponding displacement noise of the proposed CDT is 0.1 pm/Hz1/2.

AB - Capacitive displacement transducers (CDTs) have been widely used in many physical sensors, attributing to high-resolution, simple electricity and easy manufacturing process. Gap-variation CDTs generally have higher displacement resolution due to small electrode gaps but suffer from the pull-in effect, the nonlinear effect and squeeze-film damping; whereas area-variation CDTs have intrinsically good linearity and much smaller slide-film damping. However, the parallel-plate-based area-variation CDTs have the electrode width much larger than the electrode gap with negligible fringe effect; therefore, the sensitivity is limited by periodic electrode numbers. In this paper, we introduce a novel fringe-effect dominated area-variation CDT with a much higher sensitivity within a certain electrode-deployable area. Both theoretical and numerical analysis are applied to investigate the working principle of the CDT design. The proposed fringe-effect-based CDT benefits from a much larger capacitance-to-displacement sensitivity than the traditional periodic array parallel-plate-based CDT, due to the more displacement-sensitive fringe field and more deployable electrode periods. A set of experiments are designed, and the proposed area-variation CDTs are evaluated. Experimental results suggested that the proposed CDT design, which had equal electrode width, separation and gap, could universally be applied to sensors with different featured dimensions either in macroscale or microscale. Angular misalignments with both out-of-plane tilts and in-plane rotations, which affect the output offset and sensitivity, should be minimized or alleviated. The proposed fringe-effect-based CDT are successfully applied to a single-axis in-plane sensing micro-electromechanical systems (MEMS) accelerometer, showing a noise floor as low as 0.25 ng/Hz1/2 @1 Hz. The corresponding displacement noise of the proposed CDT is 0.1 pm/Hz1/2.

KW - Accelerometer

KW - Capacitive sensor

KW - Displacement transducer

KW - Fringe effect

KW - MEMS

UR - http://www.scopus.com/inward/record.url?scp=85077807647&partnerID=8YFLogxK

U2 - 10.1109/ACCESS.2019.2947570

DO - 10.1109/ACCESS.2019.2947570

M3 - Article

AN - SCOPUS:85077807647

SN - 2169-3536

VL - 7

SP - 153650

EP - 153659

JO - IEEE Access

JF - IEEE Access

M1 - 8873587

ER -