• Title/Summary/Keyword: Capacitive sensor

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The Design and fabrication of Capacitive Humidity Sensor Having Interdigital Electrodes and Its Signal Processing Circuit (빗살전극형 정전용량형 습도센서와 그 신호처리회로의 설계 제작)

  • Kang, Jeong-Ho;Lee, Jae-Yong;Kim, Woo-Hyun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.55 no.1
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    • pp.26-30
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    • 2006
  • For the purpose of developing capacitive humidity sensor having interdigital electrodes, interdigital electrode was modeled and simulated to obtain capacitance and sensitivity as a function of geometric parameters like the structural gap and thickness. For the development of ASIC, switched capacitor signal processing circuits for capacitive humidity sensor were designed and simulated by Cadence using $0.25{\mu}m$ CMOS process parameters. The signal processing circuits are composed of amplifier for voltage gain control, and clock generator for sensor driving and switch control. The characteristics of the fabricated sensors are; 1) sensitivity is 9fF/%R.H., 2) temperature coefficient of offset(TCO) is $0.4%R.H./^{\circ}C$, 3) nonlinearity is 1.2%FS, 4) hysteresis is 1.5%FS in humidity range of $3%R.H.{\sim}98%R.H.$. The response time is 50 seconds in adsorption and 70 seconds in desorption. Fabricated process used in this capacitive humidity sensor having interdigital electrode are just as similar as conventional IC process technology. Therefore this can be easily mass produced with low cost, simple circuit and utilized in many applications for both industrial and environmental measurement and control system, such as monitoring system of environment, automobile, displayer, IC process room, and laboratory etc.

The Design and Fabrication of Capacitive Humidity Sensor Having Interdigit Electrodes and its Signal Conditional Circuitry (빗살형 전극을 가지는 정전용량형 습도센서와 그 신호처리회로의 설계와 제작)

  • Park, Se-Kwang;Kang, Jeong-Ho;Park, Jin-Su
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.50 no.3
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    • pp.144-148
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    • 2001
  • For the purpose of developing capacitive humidity sensor having interdigit electrodes, interdigit electrode was modeled and simulated to obtain capacitance and sensitivity as a function of geometric parameters like the structural gap and thichness. For the development of ASIC, switched capacitor signal conditioning circuits for capacitive humidity sensor were designed and simulated by cadence using 0.25um CMOS process parameters. The signal conditioning circuits are composed of amplifier for voltage gain control, and clock generator for sensor driving and switch control The characteristics of the fabricated sensors are; 1) sensitivity is 9fF/%R.H., 2) temperature coefficient of offset(TCO) is 0.4%R.H./$^{\circ}C$, 3) nonlinearity is 1.2%FS, 4) hysteresis is 1.5%FS in humidity range of 3%R.H. ${\sim}$ 98%R.H.. The response time is 50 seconds in adsorption and 70 seconds in desorption. Fabricated process used in this capacitive humidity sensor having interdigit electrode are just as similar as conventional IC process technology. Therefore this can be easily mass produced with low cost, simple circuit and utilized in many applications for both industrial and environmental measurement and control system, such as monitoring system of environment, automobile, displayer, IC process room, and laboratory etc..

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Effects of the Electrical Characteristics of Capacitive Relative Humidity Sensor by Polyimide Film and Upper Electrode Grain by Sputtering Method (폴리이미드 박막과 스퍼터링 방법으로 증착한 상부금속 그레인이 용량형 습도센서의 전기적 특성에 미치는 영향)

  • Lee, Jin-Min
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.3
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    • pp.224-228
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    • 2011
  • This research, integratable capacitive relative humidity sensor was produced using polyimide on glass substrate. Also, at the time of upper electrode formation, upper electrode grain size was affected by giving changes to sputtering condition. Through this analyzing electrical characteristics affect from capacitive relative humidity sensor was possible. Capacitance of capacitive relative humidity sensor was 330 pF, linearity of 0.6%FS and it showed less than 3% of low hysterisis. Specially, hysterisis was affected more from interface than interstitial. Also was affected by the grain size which is one of the formation condition of upper electrode.

CALIBRATION OF A NEW CAPACITIVE TORQUE SENSOR FOR MEASURING BASIC MAGNETIC CHARACTERISTICS WITH ELECTROMAGNETIC AND GRAVITATIONAL FORCES

  • Kim, M.Y.;Choi, K.L.;Choi, S.J.;Song, E.Y.;Lee, Y.H.;Hee, J.R.
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.786-789
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    • 1995
  • With a newly designed capacitive torque sensor a multipurpose magnetometer for measuring basic magnetic characteristics such as hyteresis loops, magnetic anisotropy and magnetostriction was built. In order to calibrate the capacitive torque sensor, we measured the output voltages of the sensor by applying the torques due to the electromagnetic and gravitational forces. Experimental results of the several calibration method for the capacitive torque sensor showed good agreement within 3 %.

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A Disk-type Capacitive Sensor for Five-dimensional Motion Measurements (5 차원 변위 측정용 원판형 정전용량 센서)

  • Ahn, Hyeong-Joon;Park, Jung-Ho;Um, Chang-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.655-662
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    • 2007
  • This paper presents a disk-type capacitive sensor for simultaneous measurement of five-dimensional motions of a target. The sensor can be manufactured with a printed circuit board (PCB) such that the sensor can be integrated with its electronics in a single PCB board, whereby the manufacturing costs is considerably reduced. The sensor is optimally designed through an error analysis of possible mechanical errors. Furthermore, the sensor can correct the horizontal motion measurement errors due to the sensor installation tilting error. A proto-type PCB sensor, electronics and a test rig were built, and the effectiveness of the developed sensor was proved through experiments.

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Performance of Built-in Capacitance Type Transducer of a Magnetic Bearing System (캐패시턴스형 센서가 내장된 자기베어링 시스템의 작동성능에 관한 연구)

  • 장인배;한동철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2082-2088
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    • 1995
  • In this paper, we designed and fabricated the magnetic bearings and built-in type cylindrical capacitive transducers for improving the vibration characteristics of rotating shaft. The eddy current and magnetic field from the electromagnet of the bearing don't affect the measuring signal of the capacitive type transducers so that it is possible to locate the capacitive sensor plates around the magnetic bearing poles and can improve the spillover problem which is induced by the noncollocation of the sensors and actuators. According to the sensitivity calibration schemes using a X-Y table, the cylindrical capacitive transducers have a good linearities in the .+-.70.mu.m range from the geometric center of the sensor plates. The measured results also show high displacement sensitivities of the sensors. According to the performance test of the magnetic bearing which is controlled by the analog PD controllers, we found that the built-in capacitive transducer system successfully measures the journal displacement in the magnetic field and therefore the magnetic bearing system supports the rotating shaft up to 12,000 rpm.

PD Detection in Air by Capacitive Electric Field Sensor (전계센서의 원리를 이용한 공기중 부분방전신호 검출)

  • Lee, Y.H.;Lee, K.W.;Park, S.H.;Kang, S.H.;Shin, Y.S.;Lim, K.J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07b
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    • pp.900-903
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    • 2002
  • Partial discharges(PD) in air, corona discharges, deteriorate the insulation strength. So, it is necessary to detect PD at an early stage before the system failure and extensive damage to the equipment. PD emit signals which can be detected by applying an capacitive electric field diagnosis. In this paper, We measured signals by capacitive electric field sensor and analyzed FFT from PD, and then compared conventional electric PD detecting method to capacitive electric field diagnosis by $\Psi-q-n$, $\Psi-v-n$, $\Psi-n$, $\Psi-q$ distributions.

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Capacitive sensor for the detection of residual quantity of intravenous drip solution in a plastic intravenous bag

  • Wei, Qun;Woo, Sang-Hyo;Mohy-Ud-Din, Zia;Kim, Dong-Wook;Won, Chul-Ho;Cho, Jin-Ho
    • Journal of Sensor Science and Technology
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    • v.19 no.4
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    • pp.271-277
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    • 2010
  • Intravenous(IV) drip therapy is extensively used for all kinds of treatments. It works by delivering medicine directly into the vein. When the medicine has been fully dispensed, a dangerous situation occurs since air in the IV drip bag could enter the patient's vein, which is hazardous to the patient’s safety. In this paper, using capacitive sensors to detect the residual quantity of a plastic IV drip pack is proposed. A simulation model of this technology was shown by a finite elements analysis(FEA) program to find out its feasibility and analyze the proper geometrical dimension of a capacitive sensor. According to the FEA simulation, 3 kinds of capacitive sensors were attached to the bottom surface of the plastic IV drip bag to detect the residual quantity in the experiment. Experimental data showed an agreement with the FEA simulation model estimation and confirmed that the sensor works.

Capacitive Parameter Estimation of Passive Telemetry RF Sensor System Using RLS Algorithm (RLS 알고리즘을 이용한 원격 RF 센서 시스템의 정전용량 파라메타 추정)

  • Kim, Kyung-Yup;Lee, John-Tark
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.5
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    • pp.858-865
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    • 2008
  • In this paper, Capacitive Telemetry RF Sensor System using Recursive Least Square (RLS) algorithm was proposed. General Telemetry RF Sensor System means that it should be "wireless", "implantable" and "batterless". Conventional Telemetry RF Sensor System adopts Integrated Circuit type, but there are many defects like complexity of structure and the limitation of large power consumption in some cases. In order to overcome these disadvantages, Telemetry RF Sensor System based on inductive coupling principle was proposed in this paper. Proposed Telemetry RF Sensor System is very simple because it consists of R, L and C and measures the changes of environment like pressure and humidity in the type of capacitive value. This system adopted RLS algorithm for estimation of this capacitive parameter. For the purpose of applying RLS algorithm, proposed system was mathematically modelled with phasor method and was quasi-linearized. As two parameters such as phase and amplitude of output voltage for estimation were needed, Phase Difference Detector and Amplitude Detector were proposed respectively which were implemented using TMS320C2812 made by Texas Instrument. Finally, It is verified that the capacitance of proposed telemetry RF Sensor System using RLS algorithm can be estimated efficiently under noisy environment.

A Design of Capacitive Sensing Touch Sensor Using RC Delay with Calibration (캘리브래이션 기능이 있는 RC지연 정전용량 방식 터치센서 설계)

  • Seong, Kwang-Su;Lee, Mu-Jin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.8
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    • pp.80-85
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    • 2009
  • In this paper, we propose a full digital capacitive sensing touch key reducing the effects due to the variations of resistance and clock frequency. The proposed circuit consists of two capacitive loads to measure and a resistor between the capacitive loads. The method measures the delays of the resistor and two capacitive loads, respectively. The ratio of the two delays is represented as the ratio of the two capacitive loads and is irrelative to the resistance and the clock frequency if quantization error is disregarded. Experimental results show the proposed scheme efficiently reduces the effects due to the variations of clock frequency and resistance. Further more the method has 1.04[pF] resolution and can be used as a touch key.