• Title/Summary/Keyword: MEMS 센서

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The fabrication of bolometric IR detector for glucose concentration detection (글루코오스 농도 측정을 위한 볼로미터 타입의 적외선 센서 제작)

  • Choi, Ju-Chan;Jung, Ho;Park, Kun-Sik;Park, Jong-Moon;Koo, Jin-Gun;Kang, Jin-Yeong;Kong, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.17 no.4
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    • pp.250-255
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    • 2008
  • A vanadium pentoxide ($V_2O_5$)-based bolometric infrared (IR) sensor has been designed and fabricated using micro electro mechanical systems (MEMS) technology for glucose detection and its resistive characteristics has been illustrated. The proposed bolometric infrared sensor is composed of the vanadium pentoxide array that shows superior temperature coefficient of resistance (TCR) and standard silicon micromachining compatibility. In order to achieve the best performance, deposited $V_2O_5$ thin film is optimized by adequate rapid thermal annealing (RTA) process. Annealed vanadium oxide thin film has demonstrated a linear characteristic and relatively high TCR value (${-4}%/^{\circ}C$). The resistance of vanadium oxide is changed by IR intensity based on glucose concentration.

Numerical Analysis on the Design of a Thermal Mass Air Flow Sensor with Various Heating Modes (가열모드에 따른 열식 질량유량센서의 설계 해석)

  • Jeon, Hong-Kyu;Lee, Joon-Sik;Park, Byung-Kyu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.10
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    • pp.876-883
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    • 2007
  • Numerical simulations are conducted for the design of a micro thermal mass air flow sensor (MAFS), which consists of a microfabricated heater and thermopiles on the silicon-nitride ($Si_3N_4$) thin membrane structure. It is important to find the proper locations of these thermal elements in the design of MAFS with improved sensitivity. Three heating modes of the micro-heater are considered: constant temperature, constant power and heating pulses. The analyses are focused on the membrane temperature profile near the sensing section. Considered are the practical flow velocities, ranging from 3 m/s to 35 m/s, and the corresponding Reynolds numbers from 1000 to 10000. The results show that one of optimum sensing locations is about $100{\mu}m$ away from the microheater. It is concluded that the heating mode and configurations of thermal elements are the main factors for the MAFS with higher sensitivity.

Micro flow sensor using polycrystalline silicon carbide (다결정 실리콘 카바이드를 이용한 마이크로 유량센서)

  • Lee, Ji-Gong;Lei, Man I;Lee, Sung-Pil;Rajgopal, Srihari;Mehregany, Mehran
    • Journal of Sensor Science and Technology
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    • v.18 no.2
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    • pp.147-153
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    • 2009
  • A thermal flow sensor has been fabricated and characterized, consisting of a center resistive heater surrounded by two upstream and one downstream temperature sensing resistors. The heater and temperature sensing resistors are fabricated from nitrogen-doped(n-type) polycrystalline silicon carbide(poly-SiC) deposited by LPCVD(low pressure chemical vapor deposition) on LPCVD silicon nitride films on a Si substrate. Cavities were etched into the Si substrate from the front side to create suspended silicon nitride membranes carrying the poly-SiC elements. One upstream sensor is located $50{\mu}m$ from the heater and has a sensitivity of $0.73{\Omega}$/sccm with ${\sim}15\;ms$ rise time in a dynamic range of 1000 sccm. N-type poly-SiC has a linear negative temperature coefficient and a TCR(temperature coefficient of resistance) of $-1.24{\times}10^{-3}/^{\circ}C$ from room temperature to $100^{\circ}C$.

Optical Temperature Sensor Based on the Etched Planar Waveguide Bragg Grating Considering Linear Thermo-optic Effect (평면 광도파로 상의 식각 브래그 격자를 이용한 광온도 센서의 개발)

  • Kook-Chan Ahn;Sang-Mae Lee
    • Journal of the Korean Society of Safety
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    • v.16 no.2
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    • pp.121-129
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    • 2001
  • This paper demonstrates the development of optical temperature sensor based on the etched planar waveguide Bragg grating. Topics include design and fabrication of the etched planar waveguide Bragg grating, investigation of the grating reflection characteristics, and temperature measurement capabilities. The typical bandwidth and reflectivity of the surface etched grating has been ~0.2nm and ~7%, respectively, at a wavelength of ~1552nm. The temperature-induced wavelength change of the optical sensor is found to be slightly non-linear over ~20$0^{\circ}C$ temperature range. Theoretical models for the grating response of the sensor based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

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Parylene membrane based chemomechanical explosive sensor (패럴린 박막을 이용한 기계화학적 폭발물 센서)

  • Shin, Jae-Ha;Lee, Sung-Jun;Cha, Mi-Sun;Kim, Mun-Sang;Lee, Jung-Hoon
    • Journal of Sensor Science and Technology
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    • v.19 no.6
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    • pp.497-503
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    • 2010
  • This paper reports a chemomechanical explosive sensor based on a thin polymer membrane. The sensor consists of thin parylene membrane and electrodes. Parylene membrane is functionalized with 4-mercaptophenol which interacts strongly with nitrotoluene based explosives. The membrane deflection caused by molecular interaction between the surface and explosives is monitored by capacitance between the membrane and the substrate. To measure the capacitance, electrodes are formed on the membrane and the substrate. While the previous cantilever system requires a bulky optical measuring system, this purely electric monitoring method offers a compact and effective system. Thus, this explosive sensor can be readily miniaturized and used in the field. The developed sensor can reliably detect dinitrotoluene and its limit of detection is evaluated as approximately 110 ppb.

Fabrication of NO sensor integrated SiC micro heaters for harsh environments and its characteristics (SiC 마이크로 히터가 내장된 극한 환경용 NO 센서의 제작과 특성)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of Sensor Science and Technology
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    • v.19 no.3
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    • pp.197-201
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    • 2010
  • This paper describes the fabrication and characteristics of a NO sensor using ZnO thin film integrated 3C-SiC micro heater based on polycrystalline 3C-SiC thin film of operation in harsh environments. The sensitivity, response time, and operating properties in high temperature and voltages of NO sensors based SiC MEMS are measured and analyzed. The sensitivity of device with pure ZnO thin film at the heater operating power of 13.5 mW ($300^{\circ}C$) is 0.875 in NO gas concentration of 0.046 ppm. In the case of Pt doping, the sensitivity of at power consumption of 5.9 mW ($250^{\circ}C$) was 1.92 at same gas flow rate. The ZnO with doped Pt was showed higher sensitivity, lower working temperature and faster adsorption characteristics to NO gas than pure ZnO thin film. The NO gas sensor integrated SiC micro heater is more strength than others in high voltage and temperature environments.

Development of Dielectric Constant Sensor for Measurementof Lubricant Properties (윤활유 물성 측정을 위한 유전상수 센서 개발)

  • Hong, Sung-Ho;Kang, Moon-Sik
    • Tribology and Lubricants
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    • v.37 no.6
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    • pp.203-207
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    • 2021
  • This study presents the development of dielectric constant sensors to measure lubricant properties. The lubricant oil sensor is used to measure oil properties and machine conditions. Various condition monitoring methods are applied to diagnose machine conditions. Machine condition monitoring using oil sensors has advantage over other machine condition monitoring methods. The fault conditions can be noticed at the early stages by the detection of wear particles using oil sensors. Therefore, it provides an early warning in the failure procedure. A variety of oil sensors are applied to check the machine condition. Among all oil sensors, only one sensor can measure the tendency of several properties such as acidity and water content. A dielectric constant sensor is also used to measure various oil properties; therefore, it is very useful. The dielectric constant is the ratio of the capacitance of a capacitor using that material as a dielectric to that of a similar capacitor using vacuum as its dielectric. The dielectric constant has an effect on water content, contaminants, base oil, additive, and so forth. In this study, the dielectric constant sensor is fabricated using MEMS process. In the fabrication process, the shape, gap of the electrode array, and thickness of the insulation material are considered to improve the sensitivity of the sensor.

Development of Integration Pressure Sensor Using Piezoresistive Effect of Chemical Vapor Deposition (CVD) Produced Multilayer Graphene (CVD공정으로 제작된 멀티레이어 그래핀의 압저항 효과를 이용한 직접화된 압력센서 개발)

  • Dae-Yun Lim;Tae Won Ha;Chil-Hyoung Lee
    • Journal of Sensor Science and Technology
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    • v.32 no.6
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    • pp.470-474
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    • 2023
  • In this study, a diaphragm-type pressure sensor was developed using multi-layer(four-layer) graphene produced at 1 nm thickness by thermally transferring single-layer graphene produced by chemical vapor deposition (CVD) to a 6" silicon wafer. By measuring the gauge factor, we investigated whether it was possible to produce a pressure sensor of consistent quality. As a result of the measurement, the pressure sensor using multilayer graphene showed linearity and had a gauge factor of about 17.5. The gauge factor of the multilayer graphene-based pressure sensor produced through this study is lower than that of doped silicon, but is more sensitive than a general metal sensor, showing that it can be sufficiently used as a commercialized sensor.

The Fabrication and Characteristics of RTD(Resistance Thermometer Device) for Micro Thermal Sensors (마이크로 열 센서용 측온저항체 온도센서의 제작 및 특성)

  • Chung, Gwiy-Sang;Hong, Seog-Woo
    • Journal of Sensor Science and Technology
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    • v.9 no.3
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    • pp.171-176
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    • 2000
  • The physical and electrical characteristics of MgO and Pt thin-films on it, deposited by reactive sputtering and rf magnetron sputtering, respectively, were analyzed with annealing temperature and time by four-point probe, SEM and XRD. Under annealing conditions of $1000^{\circ}C$ and 2 hr, MgO thin-film had the properties of improving Pt adhesion to $SiO_2$ and insulation without chemical reaction to Pt thin-film, and the sheet resistivity and the resistivity of Pt thin-film deposited on it were $0.1288\;{\Omega}/{\square}$ and $12.88\;{\mu}{\Omega}{\cdot}cm$, respectively. We made Pt resistance pattern on $SiO_2$/Si substrate by lift-off method and fabricated thin-film type Pt-RTD(resistance thermometer device) for micro thermal sensors by Pt-wire, Pt-paste and SOG(spin-on-glass). In the temperature range of $25{\sim}400^{\circ}C$, the TCR value of fabricated Pt-RTD with thickness of $1.0{\mu}m$ was $3927\;ppm/^{\circ}C$ close to the Pt bulk value. Resistance values were varied linearly within the range of measurement temperature.

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바이오 센서 응용을 위한 Tree-like 실리콘 나노와이어의 표면성장 및 특성파악

  • An, Chi-Seong;Kulkarni, Atul;Kim, Ho-Jung;Kim, Tae-Seong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.08a
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    • pp.346-346
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    • 2011
  • 실리콘 나노와이어는 높은 표면적으로 인해 뛰어난 감지 능력을 가지는 재료 중 하나로 다양한 센서 응용 분야에 사용되고 있다. 이를 제작하는 방법에는 Micro Electro Mechanical Systems (MEMS) 공정을 이용한 Top-down 방식과 Vapor-Liquid-Solid (VLS) 공정을 이용한 Bottom-up 방식이 널리 사용되고 있다. 특히 Plasma-Enhanced Chemical Vapor Deposition(PECVD)와 Au 촉매를 이용한 Bottom-up 방식은 수십 나노미터 이하의 실리콘 나노와이어를 간단한 변수 조절을 통해 성장시킬 수 있다. 또한 Au/Si의 공융점인 363$^{\circ}C$보다 낮은 온도에서 $SiH_4$를 분해시킬 수 있어 열적 효과로 인한 손실을 줄일 수 있는 장점을 지니고 있다. 하지만 PECVD를 이용한 실리콘 나노와이어 성장은 VLS 공정을 통해 표면으로부터 수직으로 성장하게 되는데 이는 센서 응용을 위한 전극 사이의 수평 연결 어려움을 지니고 있다. 따라서 이를 피하기 위한 표면 성장된 실리콘 나노와이어가 요구된다. 본 연구에서는 PECVD VLS 공정을 이용하여 $HAuCl_4$를 촉매로 이용한 표면 성장된 Tree-like 실리콘 나노와이어를 성장시켰다. 공정가스로는 $SiH_4$와 이를 분해시키기 위해 Ar 플라즈마를 사용 하였고 웨이퍼 표면에 HAuCl4를 분사하고 고진공 상태에서 챔버 기판을 370$^{\circ}C$까지 가열한 후 플라즈마 파워(W) 및 공정 압력(mTorr)을 변수로 두어 실험을 진행하였다. 기존의 보고된 연구와 달리 환원된 금 입자 대신 $HAuCl_4$용액을 그대로 사용하였는데 이는 표면 조도(Surface roughness)를 가지는 Au 박막 상태로 존재하게 된다. 이 중 마루(Asperite) 부분에 PECVD로부터 발생된 실리콘 나노 입자가 상대적으로 높은 확률로 흡착하게 되어 실리콘 나노와이어의 표면성장을 유도하게 된다. 성장된 실리콘 나노와이어는 SEM과 EDS를 이용하여 직경, 길이 및 화학적 성분을 측정하였다. 직경은 약 100 nm, 길이는 약 10 ${\mu}m$ 정도로 나타났으며 Tree-like 실리콘 나노와이어가 성장되었다. 향후 전극이 형성된 기판위에 이를 직접 성장시킴으로써 이 물질의 I-V 특성을 파악 할 것이며 이는 센서 응용 분야에 도움이 될 것으로 기대된다.

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