• Title/Summary/Keyword: Humidity sensor

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Evaluation of DC Resistive Humidity Sensors Based on Conductive Carbon Ink (전도성 카본 잉크를 이용한 직류 저항형 습도센서 제작 및 평가)

  • An, Taechang
    • Journal of Sensor Science and Technology
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    • v.26 no.6
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    • pp.397-401
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    • 2017
  • A DC resistance type humidity sensor using conductive carbon ink was fabricated and its performance was evaluated. The humidity sensor was fabricated using a screen printing technique and have a structure that does not require additional metal electrodes to measure resistance change. To evaluate the performance of the humidity sensor, we measured the DC resistance change under various relative humidity levels. The fabricated humidity sensor showed a resistance change of about $2.5{\sim}50k{\Omega}$ in 11 ~ 95% RH environment. It also shows a linear relationship in the relative humidity versus log DC resistance graph. In comparison with commercial humidity sensor under real environment, it can be confirmed that the resistance of the humidity sensor changes to almost the same level as the measured humidity. These results show that the resistance type humidity sensor can be operated stably in actual environment.

A Development of the Humidity Sensor and Controller Using High Frequency Resistance Method for Hopper-Scale (호퍼스케일용 고주파 저항방식의 습도센서 및 컨트롤러 개발)

  • 서양오;이창근;이동철;홍연찬
    • Proceedings of the IEEK Conference
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    • pp.163-166
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    • 2000
  • This paper describes the principle of humidity sensor using high frequency resistance method for Hopper-Scale that is used in RPC(Rice processing Complex) which is spreaded out in domestic, and we also understand the principle and specificity of controller and humidity sensor. After artworking the humidity sensor and controller circuit, we measure the humidity of the designed system. In this progress, we suggested substitute parts which are easy to get in domestic and also we could propose correct method of humidity detection.

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An Integrated Sensor for Pressure, Temperature, and Relative Humidity Based on MEMS Technology

  • Won Jong-Hwa;Choa Sung-Hoon;Yulong Zhao
    • Journal of Mechanical Science and Technology
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    • v.20 no.4
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    • pp.505-512
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    • 2006
  • This paper presents an integrated multifunctional sensor based on MEMS technology, which can be used or embedded in mobile devices for environmental monitoring. An absolute pressure sensor, a temperature sensor and a humidity sensor are integrated in one silicon chip of which the size is $5mm\times5mm$. The pressure sensor uses a bulk-micromachined diaphragm structure with the piezoresistors. For temperature sensing, a silicon temperature sensor based on the spreading-resistance principle is designed and fabricated. The humidity sensor is a capacitive humidity sensor which has the polyimide film and interdigitated capacitance electrodes. The different piezoresistive orientation is used for the pressure and temperature sensor to avoid the interference between sensors. Each sensor shows good sensor characteristics except for the humidity sensor. However, the linearity and hysteresis of the humidity sensor can be improved by selecting the proper polymer materials and structures.

A Highly Sensitive Humidity Sensor Using a Modified Polyimide Film

  • Kim, Yong-Ho;Lee, Joon-Young;Kim, Yong-Jun;Kim, Jung-Hyun
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.4 no.2
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    • pp.128-132
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    • 2004
  • This paper presents the design, fabrication sequence and measurement results of a highly sensitive capacitive-type humidity sensor using a polyimide film without hydrophobic elements. The structure of the humidity sensor is MIM (metalinsulator-metal). For a high sensitivity, a modified aromatic polyimides as a moisture absorbing layer has been synthesized instead of using general polyimides containing hydrophobic elements. The polyimide film was obtained by synthesizing and thermally polymerizing polyamic acid composed of m-pyromellitic dianhydride, phenelenediamine and dimethylacetamide. Characteristics of fabricated sensors which include sensitivity, hysteresis and stability have been measured. The measurement result shows the percent normalized capacitance change of 0.37/%RH over a range from 10 to 90%RH, hysteresis of 0.77% over the same %RH range and maximum drift of 0.25% at 50%RH. The result shows that the developed humidity sensor can be applied to evaluate a hermeticity of various sensors and actuator systems as well as micro packages.

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.

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.

A Capacitive Type Humidity Sensor Using a Polyimide Film for Hermeticity Measurement of Micro Packages (마이크로 패키지의 밀폐도 측정을 위한 정전용량형 폴리이미드 습도센서)

  • Kim, Yong-Ho;Kim, Yong-Jun;Kim, Kyung-Il;Kim, Joong-Hyun
    • Journal of Sensor Science and Technology
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    • v.13 no.4
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    • pp.287-291
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    • 2004
  • A capacitive type humidity sensor has been fabricated using a polyimide film without hydrophobic elements and its characteristics has been evaluated for hermeticity measurement of micro packages. For a highly sensitive humidity sensor, a polyimide film without hydrophobic elements has been synthesized and used instead of using a commercial one in which 7 group elements such as fluorine or chlorine are included. Sensitivity, stability and hysteresis has been performed to characterize the fabricated sensors. The sensitivity defined as normalized percent capacitance change was 0.3751%RH and hysteresis was 0.77% in the range of 10%RH to 90%RH. Maximum deviation from the average capacitance measured for 120 minutes at 50%RH was 0.25%. The proposed humidity sensor can be used for hermeticity measurement of micro packages.

Passive Telemetry Capacitive Humidity Sensor System using RLSE Algorithm (RLSE알고리즘을 이용한 원격 정전용량형 습도 센서 시스템)

  • Kyung-Yup Kim;Joon-Tark Lee
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.4
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    • pp.569-576
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    • 2004
  • In this paper, passive telemetry capacitive humidity sensor system using a RLSE(Recursive Least Square Estimation) technique is proposed. To overcome the problem like power limits and complications that general passive telemetry sensor system including IC chip has, the principle of inductive coupling is applied to model the sensor system. Specially. by applying the forgetting factor we show that the accuracy of its estimation can be improved even in the case of time varying parameter and also the convergence time can be reduced.

Plasma Process Effect and Selectivity Characteristics of Carbon Nanotube Film Humidity Sensor (CNT 습도센서의 플라즈마처리 효과와 선택성 특성)

  • Park, Chan-Won
    • Journal of Industrial Technology
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    • v.33 no.A
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    • pp.67-72
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    • 2013
  • CNT(carbon nanotube) humidity sensors with plasma treated electrodes exhibit a much faster response time and a higher sensitivity to humidity, compared to untreated CNT and porous Cr electrodes. These results may be partially due to their percolated pore structure being more accessible for water molecules and for expending the diffusion of moisture to the polyimide sensing film, and partially due to the oxygenated surface of CNT films. This paper shows a plasma process effect and selectivity characteristics of CNT film humidity sensor.

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Characteristics of SAW humidity sensor using nanocrystalline ZnO films

  • Hong, Hoang-Si;Chung, Gwiy-Sang
    • Journal of Sensor Science and Technology
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    • v.19 no.5
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    • pp.337-341
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    • 2010
  • In this work, the nanocrystalline ZnO/polycrystalline(poly) aluminum nitride(AlN)/ Si-layered structure was fabricated for humidity sensor applications based on surface acoustic wave(SAW). The ZnO film was used as a sensitive material layer. The ZnO and AlN(0002) were deposited by a sol-gel process and a pulse reactive magnetron sputtering, respectively. The ZnO sensitive films coated on AlN have a hexagonal wurtzite structure after the thin films annealed at $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$. The surface of the film exhibits sponginess and a nanometer particle size(below 50 nm). The largest shift in the frequency response was at approximately 200 kHz(the relative humidity: 10 %~90 %) for the structure annealed at $400^{\circ}C$. The effect of the change in the environmental temperature on the frequency response of the SAW humidity sensor was also investigated.