• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2003년도 춘계학술발표논문집
• /
• pp.119-121
• /
• 2003

마이크로 가스센서를 개발하기 위하여 가장 핵심적인 부품인 마이크로 핫플레이트에 대한 열전달을 해석하였다. 상용 열유동 해석 전용 프로그램인 FUENT를 이용하여 발열부와 주위의 실리콘 기판의 온도분포를 구하였다. 발열부에서는 전기저항에 의해서 일정한 양의 열이 균일하게 발생한다고 가정하고 그 열이 실리콘 기판의 끝을 통하여 빠져나간다고 가정하여 정상상태의 온도분포를 구하였다. 해석한 온도분포를 이용하여 균일한 온도분포를 얻을 수 있도록 발열선의 배치를 변화시켜가며 마이크로 핫플레이트의 설계를 완성하였다.

• 센서학회지
• /
• 제14권2호
• /
• pp.69-77
• /
• 2005

The electronic nose (e-nose) has been used in food industry and quality controls in plastic packaging. Recently it finds its applications in medical diagnosis, specifically on detection of diabetes, pulmonary or gastrointestinal problem, or infections by examining odors in the breath or tissues with its odor characterizing ability. Moreover, the use of portable e-nose enables the on-site measurements and analysis of vapors without extra gas-sampling units. This is expected to widen the application of the e-nose in various fields including point-of-care-test or e-health. In this study, a PDA-based portable e-nose was developed using micro-machined gas sensor array and miniaturized electronic interfaces. The rich capacities of the PDA in its computing power and various interfaces are expected to provide the rapid and application specific development of the diagnostic devices, and easy connection to other facilities through information technology (IT) infra. For performance verification of the developed portable e-nose system, Six different vapors were measured using the system. Seven different carbon-black polymer composites were used for the sensor array. The results showed the reproducibility of the measured data and the distinguishable patterns between the vapor species. Additionally, the application of two typical pattern recognition algorithms verified the possibility of the automatic vapor recognition from the portable measurements. These validated the portable e-nose based on PDA developed in this study.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 G
• /
• pp.3319-3321
• /
• 1999

Pt-RTD and Micro Heater was fabricated by using MgO as medium layer in order to improve adhesion of Pt thin-films to $SiO_2$ layer, MgO layer improved adhesion of Pt thin-films to $SiO_2$ layer without any chemical reactions to Pt thin-films under high annealing temperatures, In the analysis of properties of Pt-RTD, TCR value had 3927 $ppm/^{\circ}C$ and liner in the temperature range of $25-400^{\circ}C$. The temperature of Pt micro-heater had up to $400^{\circ}C$ with 1.5watts of the heating power. In investigating output characteristics of flow sensors output voltages increased as gas flow rate and its conductivity increased due to increase of heat-loss from sensor to external. Output voltage was 82 mV at $N_2$ flow rate of 2000sccm, heating power of 1.2W.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.352-353
• /
• 2006

가스센서용 마이크로 히터 제작에는 표연 마이크로 머시닝 또는 벌크 마이크로머시닝 기술을 이용한다. 표면 마이크로 머시닝에 의한 마이크로 히터 (MHP) 구조의 경우, 기판과 박막간의 폭이 좁기 때문에 에칭 공정 후 세정이 잘 이루어지지 않으면 열적 절연이 잘 이루어지지 않아서 히터와 센서의 성능을 저하시키는 원인이 된다. 본 연구에서는 표면 마이크로 머시닝 기술에 의한 가스 센서용 마이크로 히터를 제작한다. $SiO_2$와 $Si_3N_4$를 성분으로 하며, $100{\mu}m\;{\times}\;100{\mu}m$의 면적과 350 nm 의 두께를 갖는 가스 센서용 마이크로 히터를 제작하였다. 이를 위하여 ANSYS를 통한 유한요소해석에 의한 열분포 해석으로 최적구조를 확인하였다. 센서로의 열 전달 효율을 높이기 위해 센서 박막은 히터 위에 적층하였다. 실리콘 표면과 마이크로 히터와의 간격은 에칭 공정을 통하여 $2{\mu}m$로 하였으며, 이 공간에서는 에칭 및 세정 후에 이물질이 깨끗이 세정되지 않고 남아 있거나, 습식 공정 중에 수분의 장력에 의한 열전연성이 나빠질 수 있는 등 단점이 있다. 이는 건식 등방성 에칭 공정을 통하여 해결하였다.

• 한국수소및신에너지학회논문집
• /
• 제17권1호
• /
• pp.69-74
• /
• 2006

Thick film $H_2$ sensors were fabricated using $SnO_2$ loaded with $Ag_2O$ and $PtO_x$. The composition that gave the highest sensitivity for $H_2$ was in the weight% ratio of $SnO_2 : PtO_x : Ag_2O$ as 93 : 1 : 6. The nano-crystalline powders of $SnO_2$ synthesized by sol-gel method were screen printed with $Ag_2O$ and $PtO_x$ on alumina substrates. The fabricated sensors were tested against gases like $H_2$, $CH_4$, $C_3H_8$, $C_2H_5OH$ and $SO_2$. The composite material was found sensitive against $H_2$ at the working temperature $130^{\circ}C$, with minor interference of other gases. The $H_2$ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on $SnO_2-Ag_2O-PtO_x$ system exhibited the high performance, high selectivity and very short response time to $H_2$ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of $H_2$.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
• /
• pp.267-268
• /
• 2006

전력소모를 감소시키기 위해 MEMS 기술을 이용하여 마이크로 히터를 제작하고 그 위에 감지물질을 도포하여 마이크로 센서를 제작하였다. 마이크로 가스센서는 $SnO_2$를 모물질로 하였으며 가스 감도를 향상시키기 위해 Pd와 Rh, ${\alpha}-Fe_2O_5$, $V_2O_5$를 첨가하여, CO 가스 강도를 조사하였다. $SnO_2$에 촉매로서 Pd만을 첨가하였을 때보다 Rh, ${\alpha}-Fe_2O_5$. $V_2O_5$등을 첨가하였을 때 CO가스에 대한 감도 반응이 우수하였다. 마이크로 가스센서의 소비전력은 42mW이었다.

• 센서학회지
• /
• 제23권5호
• /
• pp.314-319
• /
• 2014

Here, we review the various methods for the preparation of vanadium dioxide ($VO_2$) films and nanowires, and their potential applications to the sensors such as gas sensor, strain sensor, and temperature sensor. $VO_2$ is an interesting material on account of its easily accessible and sharp Mott metal-insulator transition (MIT) at ${\sim}68^{\circ}C$ in the bulk. The MIT is also triggered by the electric field, stress, magnetic field etc. This paper involves exceptionally sensitive hydrogen sensors based on the catalytic process between hydrogen molecules and Pd nanoparticles on the $VO_2$ surface, and fast responsive sensors based on the self-heating effects which leads to the phase changes of the $VO_2$. These features will be seen in this paper and can enable strategies for the integration of a $VO_2$ material in advanced and complex functional units such as logic gates, memory, FETs for micro/nano-systems as well as the sensors.

• 대한의용생체공학회:의공학회지
• /
• 제31권3호
• /
• pp.187-193
• /
• 2010

In this study we have designed and fabricated an inexpensive micro electronic system that we call Alvitek. It can indirectly but accurately predict and display the partial pressures of alveolar oxygen and carbon dioxide for the patients in the ICU of a hospital. Alvitek consists of both hardware part and software part. Performance of the system is tested by animal experiment with pigs for various $F_{t}e_{2}$ and RR(Respiratory Rate) values under the mechanical ventilation. The predicted alveolar gas partial pressures are cprpared with the approximate alveolar oxygen partial pressures easily calculated by the physician’s bedside formula. As a result, we have concluded that the relative error of A-$aDe_2$ calculated by the bedside formula grows seriously for lower $F_{t}e_{2}$ values. The present prediction method of Alvitek is henceforth believed very meaningful to the physicians. The system hardware and software are described in the text.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 D
• /
• pp.1818-1820
• /
• 1999

This paper presents direct ${\mu}c$-Si:H thin film growth on the glass substrates using RPCVD system (remote plasma chemical vapor deposition) in low temperature. Hydrogenated micro-crystalline silicon deposited by RPCVD system in low temperature is very useful material for photovoltaic devices, sensor applications, and TFTs (thin film transistors). Varying the deposition conditions such as substrate temperature, gas flow rate, reactive gas ratio $(SiH_4/H_2)$, total chamber pressure, and rf power, we deposited ${\mu}c$-Si:H thin films on the glass substrates (Corning glass 1737). And then we measured the structural and electrical properties of the films.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.45-46
• /
• 2008

There are various polluting emissions related to the air quality such as $NO_x$, $CO_2$, CO, VOCs, $O_3$, $SO_2$, $CH_4$, $H_2S$, $NH_3$, etc. We need the system that reduces emission of these environment gases and detects risk factors in modern society. Therefore, if we use the USN(Ubiquitous Sensor Network) technology and a MAV(Micro Air Vehicle) Quad Rotor which can be hovering and moving free for setting up the environment gas sensing system, the realtime measurement on environment gases is facilitated and by extension, in application of traffic watchdog, forest fire surveillance and counter-terrorism efforts, we anticipate making better use of a Quad Rotor.