Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer

In space gravitational-wave-detection missions, inertial sensors are used as the core loads, and their acceleration noise needs to reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn&g...

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Main Authors: Yanlin Sui, Tao Yu, Longqi Wang, Zhi Wang, Ke Xue, Yuzhu Chen, Xin Liu, Yongkun Chen
Format: Article
Language:English
Published: MDPI AG 2022-11-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/22/23/9284
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author Yanlin Sui
Tao Yu
Longqi Wang
Zhi Wang
Ke Xue
Yuzhu Chen
Xin Liu
Yongkun Chen
author_facet Yanlin Sui
Tao Yu
Longqi Wang
Zhi Wang
Ke Xue
Yuzhu Chen
Xin Liu
Yongkun Chen
author_sort Yanlin Sui
collection DOAJ
description In space gravitational-wave-detection missions, inertial sensors are used as the core loads, and their acceleration noise needs to reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup><mo> </mo><msup><mrow><mi>ms</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo>/</mo><msqrt><mrow><mi>Hz</mi></mrow></msqrt></mrow></semantics></math></inline-formula> at a frequency of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.1</mn><mo> </mo><mi>mHz</mi></mrow></semantics></math></inline-formula>, which corresponds to the capacitive sensing system; the capacitive sensing noise on the sensitive axis needs to reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo> </mo><mi>aF</mi><mo>/</mo><msqrt><mrow><mi>Hz</mi></mrow></msqrt></mrow></semantics></math></inline-formula>. Unlike traditional circuit noise evaluation, the noise in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>mHz</mi></mrow></semantics></math></inline-formula> frequency band is dominated by the thermal noise and the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>/</mo><mi mathvariant="normal">f</mi></mrow></semantics></math></inline-formula> noise of the device, which is a challenging technical goal. In this paper, a low-frequency, high-precision resonant capacitor bridge method based on a planar transformer is used. Compared with the traditional winding transformer, the developed planar transformer has the advantages of low temperature drift and low <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>/</mo><mi mathvariant="normal">f</mi></mrow></semantics></math></inline-formula> noise. For closed-loop measurements of capacitive sensing circuits and sensitive structures, the minimum capacitive resolution in the time domain is about <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo> </mo><mi>aF</mi></mrow></semantics></math></inline-formula>, which is far lower than the scientific measurement resolution requirement of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5.8</mn><mo> </mo><mi>fF</mi></mrow></semantics></math></inline-formula> for gravitational wave detection. The capacitive sensing noise is converted to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1.095</mn><mo> </mo><mi>aF</mi><mo>/</mo><msqrt><mrow><mi>Hz</mi></mrow></msqrt></mrow></semantics></math></inline-formula> in the frequency band of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>10</mn><mo> </mo><mi>mHz</mi><mo>–</mo><mn>1</mn><mo> </mo><mi>Hz</mi></mrow></semantics></math></inline-formula>. Although there is a gap between the closed-loop measurement results and the final index, the measurement environment is an experimental condition without temperature control on the ground; additionally, in China, the measurement integrity and actual measurement results of the capacitive sensing function have reached a domestic leading level. This is the realization of China’s future space gravitational wave exploration.
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spelling doaj.art-e53de29596424bc2a73213d0b5fb66252023-11-24T12:11:37ZengMDPI AGSensors1424-82202022-11-012223928410.3390/s22239284Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar TransformerYanlin Sui0Tao Yu1Longqi Wang2Zhi Wang3Ke Xue4Yuzhu Chen5Xin Liu6Yongkun Chen7Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaChangchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, ChinaIn space gravitational-wave-detection missions, inertial sensors are used as the core loads, and their acceleration noise needs to reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>15</mn></mrow></msup><mo> </mo><msup><mrow><mi>ms</mi></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo>/</mo><msqrt><mrow><mi>Hz</mi></mrow></msqrt></mrow></semantics></math></inline-formula> at a frequency of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.1</mn><mo> </mo><mi>mHz</mi></mrow></semantics></math></inline-formula>, which corresponds to the capacitive sensing system; the capacitive sensing noise on the sensitive axis needs to reach <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo> </mo><mi>aF</mi><mo>/</mo><msqrt><mrow><mi>Hz</mi></mrow></msqrt></mrow></semantics></math></inline-formula>. Unlike traditional circuit noise evaluation, the noise in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>mHz</mi></mrow></semantics></math></inline-formula> frequency band is dominated by the thermal noise and the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>/</mo><mi mathvariant="normal">f</mi></mrow></semantics></math></inline-formula> noise of the device, which is a challenging technical goal. In this paper, a low-frequency, high-precision resonant capacitor bridge method based on a planar transformer is used. Compared with the traditional winding transformer, the developed planar transformer has the advantages of low temperature drift and low <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>/</mo><mi mathvariant="normal">f</mi></mrow></semantics></math></inline-formula> noise. For closed-loop measurements of capacitive sensing circuits and sensitive structures, the minimum capacitive resolution in the time domain is about <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>3</mn><mo> </mo><mi>aF</mi></mrow></semantics></math></inline-formula>, which is far lower than the scientific measurement resolution requirement of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5.8</mn><mo> </mo><mi>fF</mi></mrow></semantics></math></inline-formula> for gravitational wave detection. The capacitive sensing noise is converted to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1.095</mn><mo> </mo><mi>aF</mi><mo>/</mo><msqrt><mrow><mi>Hz</mi></mrow></msqrt></mrow></semantics></math></inline-formula> in the frequency band of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>10</mn><mo> </mo><mi>mHz</mi><mo>–</mo><mn>1</mn><mo> </mo><mi>Hz</mi></mrow></semantics></math></inline-formula>. Although there is a gap between the closed-loop measurement results and the final index, the measurement environment is an experimental condition without temperature control on the ground; additionally, in China, the measurement integrity and actual measurement results of the capacitive sensing function have reached a domestic leading level. This is the realization of China’s future space gravitational wave exploration.https://www.mdpi.com/1424-8220/22/23/9284capacitive sensingplanar transformergravitational wave detection
spellingShingle Yanlin Sui
Tao Yu
Longqi Wang
Zhi Wang
Ke Xue
Yuzhu Chen
Xin Liu
Yongkun Chen
Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer
Sensors
capacitive sensing
planar transformer
gravitational wave detection
title Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer
title_full Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer
title_fullStr Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer
title_full_unstemmed Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer
title_short Analysis of a Capacitive Sensing Circuit and Sensitive Structure Based on a Low-Temperature-Drift Planar Transformer
title_sort analysis of a capacitive sensing circuit and sensitive structure based on a low temperature drift planar transformer
topic capacitive sensing
planar transformer
gravitational wave detection
url https://www.mdpi.com/1424-8220/22/23/9284
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