• Title, Summary, Keyword: Sensor sensitivity

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Sensing characteristics of Polypyrrole-based methanol sensors preparedbyin-situ vapor state polymerization

  • Linshu Jiang;Jun, Hee-Kwon;Hoh, Yong-Su;Lee, Duk-Dong;Huh, Jeung-Soo
    • Proceedings of the Materials Research Society of Korea Conference
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    • pp.137-137
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    • 2003
  • Conducting PPy/PVA composite and pure PPy gas sensors were prepared by in-situ vaporstate polymerization method in a vaporization chamber under N2 condition, by exposing the pre-coated electrode with PVA/FeC13 to distilled pyrrole monomer. The various electrical sensing behaviors of both types of sensors were systematically investigated by a flow measuring system including mass flow controller (MFC) and bubbling bottle. The FT-Raman spectroscopy of vapor state polymerized PPy was identical to that of chemically polymerized PPy, confirming the same chemical structure. Both types of sensors had positive sensitivity when exposed to methanol gas. The sensitivity varied linearly with gas concentration in the range of 50ppm to 1059ppm. The detection limit of PPy/PVA sensor was believed to be as low as 10ppm. The sensitivity of PPy/PVA composite sensor was higher than that of pure PPy sensor. Both the response time and recovery time of PPy/PVA composite sensors were longer than those of pure PPy sensors. The thickness of the sensing film affected the sensitivity this way that the sensor having thinner film had higher sensitivity, indicating that the resistance of polymer film involved in the sensing behavior was bulk resistance rather than surface resistance. The reproducibility of PPy/PVA composite sensor was excellent during eight on-off cycles by switching between N2 and 3000ppm methanol gas. The sensitivity of PPy/PVA composite sensor was only maintained for two weeks, while the sensitivity of pure PPy sensor was maintained over two months.

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BOD Determination by Heavy Metal Tolerant Candida sp. LSY2 (Candida sp. LSY2 중금속 내성주를 이용한 BOD 분석)

  • 김말남;이선영
    • Korean Journal of Environmental Biology
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    • v.17 no.4
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    • pp.415-420
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    • 1999
  • A biochemical oxygen demand (BOD) sensor loaded with Candida sp. was designed and constructed for the quick measurement of the concentrations of biologically assimilable organic substances dissolved in water. The sensitivity of the sensor was higher for glucose, acetic acid, aspartic acid and glutamic acid than that for lactose, sucrose and lactic acid. The sensitivities of BOD sensors loaded with $Zn^{2+}$ tolerant and intact strains were almost identical while the sensitivity of sensor loaded with Cd$^{2+}$ tolerant strain was considerably lower. The sensitivities of the sensors loaded with intact or $Zn^{2+}$ tolerant strains did not change with the concentration of $Cd^{2+}$ in the aqueous solution while the sensitivity of the sensor loaded with $Cd^{2+}$ tolerant strain decreased slightly. The sensitivities of the sensors loaded with intact strain, $Zn^{2+}$ or $Cd^{2+}$ tolerant strains were not affected by the concentration of $Zn^{2+}$ in the aqueous solution.n.

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Shape Design Optimization of Inductive Position Sensor to Improve Sensitivity (유도형 변위 센서의 민감도 향상을 위한 형상 최적 설계)

  • 홍준희;이동주;신우철
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.250-254
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    • 2001
  • The resolution of analog sensor is determined by its sensitivity and amplitude of noise. This paper presents modeling of inductive gap sensor base on equivalent magnetic circuit and analysis of sensitivity. We can simulate static characteristic of inductive gap sensor using this model. Computer simulation show that sensor's sensitivity is affected by magnetic flux's leakage and fringing, and that they are affected by shape of sensor probe. Base on this, we designed shape of inductive position sensor probe.

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The thermal effect on electrical capacitance sensor for two-phase flow monitoring

  • Altabey, Wael A.
    • Structural Monitoring and Maintenance
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    • v.3 no.4
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    • pp.335-347
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    • 2016
  • One of major errors in flow rate measurement for two-phase flow using an Electrical Capacitance Sensor (ECS) concerns sensor sensitivity under temperature raise. The thermal effect on electrical capacitance sensor (ECS) system for air-water two-phase flow monitoring include sensor sensitivity, capacitance measurements, capacitance change and node potential distribution is reported in this paper. The rules of 12-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance and sensitivity map the basis of Air-water two-phase flow permittivity distribution and temperature raise are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. The cross-sectional void fraction as a function of temperature is determined from the scripting capabilities in ANSYS simulation. The results show that the temperature raise had a detrimental effect on the electrodes sensitivity and sensitive domain of electrodes. The FE results are in excellent agreement with an experimental result available in the literature, thus validating the accuracy and reliability of the proposed flow rate measurement system.

Development of Inductive and Capacitive Type Intraocular Pressure (IOP) Sensor to Improve Sensitivity and Minimize Size (민감도 향상과 센서 소형화를 위한 자기 및 용량형 안압센서의 개발)

  • Jang, Cheol In;Shin, Kyeong-Sik;Yun, Kwang-Seok;Kim, Yong Woo;Kang, Ji Yoon;Lee, Soo Hyun
    • Journal of Sensor Science and Technology
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    • v.23 no.6
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    • pp.409-415
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    • 2014
  • We had presented an inductive type intraocular pressure sensor (L-sensor) in previous work. The distance between a micro coil and a ferrite on the membrane was modulated by pressure, and as a result the inductance and resonant frequency were changed. However, L-sensor has some problems to implant in eyes. First problem is low sensitivity. When L-sensor was implanted in rabbit's eyes, resonant frequency of L-sensor was very hard to detect. Second problem is biocompatibility. Size of L-sensor is $6{\times}7{\times}1.2mm$. When L-sensor was implanted in the eyes, it caused the inflammation. Therefore, this study suggests an inductive and capacitive type IOP sensor (LCsensor). The sensitivity of the LC-sensor 27.3 kHz/mmHg under 60mmHg. It is much larger than 14 kHz/mmHg of the L-sensor. And the size of LC-sensor is 47% smaller than L-sensor. After 2 weeks from the implantation of LC-sensor into rabbit eyes, we measured the changes of resonant frequency of LC-sensor according to increased IOP by Balanced Salt Solution (BSS) injection. As a result, the sensitivity of LC-sensor in in vivo test is 25 kHz/mmHg. That is similar to the sensitivity of in vitro test.

Output Characteristics and Sensitivity Analysis of Capacitive Type Torque Sensor (정전용량방식 토크센서의 출력특성과 감도해석)

  • Lee, Shin-Pyo;Kim, Jong-Bo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.12
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    • pp.2590-2597
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    • 2002
  • A new torque measuring apparatus adopting the basic principle of a capacitive type sensor is proposed in this article. Two plate electrodes are working as a capacitive sensor, whose capacitance varies as torque is applied. One end of each plate is connected to the torque carrying shaft. Output characteristics of the torque sensor were theoretically analyzed and its validity was investigated through experiment. Calculations and calibration experiments show that the output is nonlinear, that is, the sensitivity is very high at low torque but decreases as torque increases. The sensitivity of the proposed system is about 100 times roughly higher than that of a conventional 4-strain gauge type torque sensor.

Strain-Sensing Characteristics of Multi-Walled Carbon Nanotube Sheet

  • Jung, Daewoong;Lee, Gil S.
    • Journal of Sensor Science and Technology
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    • v.22 no.5
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    • pp.315-320
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    • 2013
  • In this paper, the properties of strain sensors made of spin-capable multi-walled carbon nanotubes (MWCNTs) were characterized and their sensing mechanisms analyzed. The key contribution of this paper is a new fabrication technique that introduces a simpler transfer method compared to spin-coating or dispersion CNT. Resistance of the MWCNT sheet strain sensor increased linearly with higher strain. To investigate the effect of CNT concentration on sensitivity, two strain sensors with different layer numbers of MWCNT sheets (one and three layers) were fabricated. According to the results, the sensor with a three-layer sheet showed higher sensitivity than that with one layer. In addition, experiments were conducted to examine the effects of environmental factors, temperature, and gas on sensor sensitivity. An increase in temperature resulted in a reduction in sensor sensitivity. It was also observed that ambient gas influenced the properties of the MWCNT sheet due to charge transfer. Experimental results showed that there was a linear change in resistance in response to strain, and the resistance of the sensor fully recovered to its unstressed state and exhibited stable electromechanical properties.

A Study on Optimal Sensor Placement Using Sensitivity Analysis (민감도 해석을 이용한 센서의 최적 위치 선정에 관한 연구)

  • Son, In-Soo;Lee, Doo-Ho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.3
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    • pp.241-247
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    • 2011
  • Although intensive development continues on innovative sensor systems, there is still considerable uncertainty in deciding on the number of sensors required and their locations in order to obtain adequate information on structural behavior. This paper is concerned with the sensor locations on a beam-structure for prognostic structural health monitoring. The purpose of this study is to investigate how to determine optimal sensor placement(OSP) from the sensitivity information of a known failure mode. The sensitivity of the forced vibration response of a beam to the variation of stiffness due to a crack is calculated analytically and used to determine the optimal sensor locations for the specified failure mode. The results of this method compared with the results of different OSP methods. The results have shown that the proposed method on optimal sensor placement is very effective in structural health monitoring.

Implementation of an Integrated Pressure-sensor System Adapted to the Optimum Sensitivity

  • Hong, Sung-Hee;Cho, Chun-Hyung
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.17 no.2
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    • pp.186-191
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    • 2017
  • An integrated pressure-sensor system was developed using the sensor-conditioning processes, which resulted in the optimum sensitivity of the pressure-sensor through the signal amplification, noise reduction, and level shift. Due to the specified characteristics among the components, such as operation range, the sensor output was generally limited compared to the full scale of the reading when coupled with other parts. Devices fabricated exhibited comparable characteristics with higher pressure sensitivity to that of the pressure sensor without sensor-conditioning process. In this work, the sensor resolution was at least enhanced at least by 25% using the sensor-conditioning processes.

A PDMS-Coated Optical Fiber Bragg Grating Sensor for Enhancing Temperature Sensitivity

  • Park, Chang-Sub;Joo, Kyung-Il;Kang, Shin-Won;Kim, Hak-Rin
    • Journal of the Optical Society of Korea
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    • v.15 no.4
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    • pp.329-334
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    • 2011
  • We proposed a poly-dimethylsiloxane (PDMS)-coated fiber Bragg grating (FBG) temperature sensor for enhancing temperature sensitivity. By embedding the bare FBG in a temperature-sensitive elastomeric polymer, the temperature sensitivity of the proposed structure could be effectively improved by 4.2 times higher than those of the conventional bare-type FBG sensors due to the high thermal expansion coefficient of the PDMS. We analyzed the temperature-sensitivity enhancement effect with the increased Bragg wavelength shift in our structure and dependence on the temperature sensitivity with respect to the cross-section area of the PDMS.