• 한국전기전자재료학회논문지
• /
• 제29권5호
• /
• pp.312-316
• /
• 2016

In this study, we fabricated $NO_x$ gas sensor by using multi-walled carbon nanotubes(MWCNT)/zinc oxide(ZnO) composite film. Carbon nanotubes (CNTs) have good electronic, chemical-stability, and sensitivity characteristics. And zinc oxide (ZnO) is a wide band gap and large exciton binding energy semiconductor. In particular, gas sensors require characteristics such as high speed, sensitivity, and selectivity. The fabricated gas sensor was used to detect $NO_x$ gas for different values of the $NO_x$ gas concentrations. The gas sensor that absorbed$NO_x$ gas molecules showed a increasing in resistance. The sensitivity of the gas sensor was increased by increasing the gas concentrations. Additionally, while changing the temperature inside the chamber for the MWCNT/ZnO composite film gas sensor, we obtained the sensitivity. And the comparison analysis to ZnO film gas sensor for detecting $NO_x$ gas. From the experiment result, we confirmed improvement of $NO_x$ gas detection characteristics using the MWCNT/ZnO composite film.

• 한국재료학회지
• /
• 제34권5호
• /
• pp.235-241
• /
• 2024

Gas identification techniques using pattern recognition methods were developed from four micro-electronic gas sensors for noxious gas mixture analysis. The target gases for the air quality monitoring inside vehicles were two exhaust gases, carbon monoxide (CO) and nitrogen oxides (NO_x), and two odor gases, ammonia (NH₃) and formaldehyde (HCHO). Four MEMS gas sensors with sensing materials of Pd-SnO₂ for CO, In₂O₃ for NO_X, Ru-WO₃ for NH₃, and hybridized SnO₂-ZnO material for HCHO were fabricated. In six binary mixed gas systems with oxidizing and reducing gases, the gas sensing behaviors and the sensor responses of these methods were examined for the discrimination of gas species. The gas sensitivity data was extracted and their patterns were determined using principal component analysis (PCA) techniques. The PCA plot results showed good separation among the mixed gas systems, suggesting that the gas mixture tests for noxious gases and their mixtures could be well classified and discriminated changes.

• 한국재료학회지
• /
• 제23권9호
• /
• pp.477-482
• /
• 2013

We investigated the detection properties of nitrogen monoxide (NO) gas using transparent p-type $CuAlO_2$ thin film gas sensors. The $CuAlO_2$ film was fabricated on an indium tin oxide (ITO)/glass substrate by pulsed laser deposition (PLD), and then the transparent p-type $CuAlO_2$ active layer was formed by annealing. Structural and optical characterizations revealed that the transparent p-type $CuAlO_2$ layer with a thickness of around 200 nm had a non-crystalline structure, showing a quite flat surface and a high transparency above 65 % in the range of visible light. From the NO gas sensing measurements, it was found that the transparent p-type $CuAlO_2$ thin film gas sensors exhibited the maximum sensitivity to NO gas in dry air at an operating temperature of $180^{\circ}C$. We also found that these $CuAlO_2$ thin film gas sensors showed reversible and reliable electrical resistance-response to NO gas in the operating temperature range. These results indicate that the transparent p-type semiconductor $CuAlO_2$ thin films are very promising for application as sensing materials for gas sensors, in particular, various types of transparent p-n junction gas sensors. Also, these transparent p-type semiconductor $CuAlO_2$ thin films could be combined with an n-type oxide semiconductor to fabricate p-n heterojunction oxide semiconductor gas sensors.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1993년도 추계 학술발표 강연 및 논문 개요집
• /
• pp.66-67
• /
• 1993

• 한국세라믹학회지
• /
• 제20권2호
• /
• pp.93-98
• /
• 1983

The sensitivity characteristics of $SnO_2$-based gas sensor prepared by sintering method have been studied at the presence of CO and Propane gas. Samples mixed with 1wt% $La_2O_3$ and 1wt% $PdCl_2$ showed highest sensitivity to CO and propane gas at 250$^{\circ}$C but the addition of $CeO_2$ did not enhance the sensitivity. For slectivity for gas a $SnO_2-La_2O_3$ (1wt%) sample without $PdCl_2$ showed better results. A sample sintered sintered at 115$0^{\circ}C$ has shown the optimum condition in sensitivity and electroding

• 센서학회지
• /
• 제24권5호
• /
• pp.311-318
• /
• 2015

The excess use and generation of various toxic gases from many industrial complexes and plant facilities have increased the possibility of leakage or explosion accidents, which can cause fatal damage to human beings in the wide range of neighboring area. To prevent the exposure to the fatal toxic gases, it is very important to monitor the leakage of toxic gases using gas sensors in real time. Various types of gas sensors, which can be classified as semiconductor, electrochemical, optical, and catalytic combustion types according to the operating principles, have been developed. In this review, the operation principles of gas sensors are explained and the performance of those sensors is compared. The state-of-the-art gas sensor technologies developed by research institutes or companies are reviewed also.

• 센서학회지
• /
• 제28권1호
• /
• pp.23-29
• /
• 2019

A copper tetracumylphenoxy phthalocyanine (CuPccp) thin film was formed on an organic insulator film by Langmuir-Blodgett (LB) deposition for gas sensor fabrication. To increase the reproducibility of film transfer, stearyl alcohol was used as a transfer promoter. The structural properties of the CuPccp layers were optically monitored through attenuated total reflection and polarization-modulated ellipsometry techniques. The average thickness of a single layer of the CuPccp LB film was measured to be 2.5 nm. Despite the role of the transfer promoter, the stability of the layer transfer was not sufficient to ensure homogeneity of the LB film. This was probably due to the presence of aggregates in the molecular structure of the CuPccp LB film. Nevertheless, copper phthalocyanine polymorphism can be greatly suppressed by the LB arrangement, which appears to contribute to the improvement of electrical conductivity. The p-type semiconductor characteristics were confirmed by Hall measurements from the CuPccp LB films.

• 센서학회지
• /
• 제27권5호
• /
• pp.352-356
• /
• 2018

This paper relates to a technology for monitoring a liquefied gas storage tank in the special gas field where demand is increasing owing to the continuous growth of related fields such as the semiconductor, display, and ICT convergence electronics industries. We have proposed a system for real - time monitoring using wireless sensor network technology, and implemented a system consisting of a sensor unit, transmitter module, and receiver module to be attached to a liquefied gas storage tank. The system was applied to LCO2 tanks among various liquefied gas storage tanks to verify the feasibility. The storage tanks employed in the experiments has capacities of 16,179 l and was 1,920 mm in inner diameter. Furthermore, the density was 1.03 g/l. The measured data were compared with reference data on the remaining gas level versus the $CO_2$ height of the surface, expressed using a conventional water meter, provided by an existing storage tank supplier. The experimental results show that the data is similar to the standard data provided by the tank supplier, and has a high accuracy and reliability within an error range of 0.03%.

• 한국산업정보학회:학술대회논문집
• /
• 한국산업정보학회 2002년도 춘계학술대회 논문집
• /
• pp.356-360
• /
• 2002

산업의 발달과 더불어 CO, $H_2$S, S $O_2$등에 의한 대기오염이 심각해져 가스중독의 위험성이 고조되었을 뿐만 아니라, 생활수준의 향상으로 부탄(C$_4$ $H_{10}$)이나 프로판(C$_3$ $H_{8}$) 등의 폭발성 탄화수소계 가스들의 수요가 급증하는 가운데 가스폭발의 위험성이 대두되고 있다. 이에 대한 방비책으로 고감도 가스센서의 개발 뿐만 아니라 가스센서를 응용한 가스검출 및 가스식별 시스템의 개발이 시급한 실정이다. 본 연구에서는 반도체식 가스센서의 선택도에 대한 문제점을 개선하는 동시에 단일 센서신호의 드리프트에 대한 영향을 최소화하기 위해 반도체식 가스센서 어레이를 구성하고, 이로부터 검지된 가스별 입력 패턴데이터를 신경 회로망(neural network)에 적용함으로써 가스의 종류를 선택적으로 인식할 수 있는 가스인식 시스템을 개발하고자 한다.다.

• 반도체디스플레이기술학회지
• /
• 제7권1호
• /
• pp.1-5
• /
• 2008

In this paper, we fabricated pressure difference type gas flow sensor using only dry etching technology by ICP-RIE(inductive coupled plasma reactive ion etching). The sensor's structure consists of a common shear stress type piezoresistive pressure sensor with an orifice fabricated in the middle of the sensor diaphragm. Generally, structure like diaphragm is fabricated by wet etching technology using TMAH, but we fabricated diaphragm by only dry etching using ICP-RIE. To equalize the thickness of diaphragm we applied insulator($SiO_2$) layer of SOI(Si/$SiO_2$/Si-sub) wafer as delay layer of dry etching. Size of fabricated diaphragm is $1000{\times}1000{\times}7\;{\mu}m^3$ and overall chip $3000{\times}3000{\times}7\;{\mu}m^3$. We measured the variation of output voltage toward the change of gas pressure to analyze characteristics of the fabricated sensor. Sensitivity of fabricated sensor was relatively high as about 1.5mV/V kPa at 1kPa full-scale. Nonlinearity was below 0.5%F.S. Over-pressure range of the fabricated sensor is 100kPa or more.