• Bulletin of the Korean Chemical Society
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• 제35권11호
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• pp.3158-3162
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• 2014

Various pyrene derivatives were synthesized and systematically examined in micelles. Synthesized mono and bispyrene derivatives were tested in micelles so that they displayed a strong excimer band and the excimer band was quenched in the presence of TNT and RDX. In the optimized condition, the binding constant for TNT of a simple dipyrene derivative 4 was increased up to $1.0{\times}10^6M^{-1}$ in cetyl trimethylammonium bromide (CTAB) micelles, which allowed for the detection of 2 ppb of TNT and 334 ppb of RDX by fluorescence titrations.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.21-26
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• 1995

Highly sensitive and mechanically stable gas sensors have been fabricated using the microfabrication and micromaching techniques. The sensing material used to detect the offensive trimethylarnine ((CH$_{3}$)$_{3}$N) gas is 6 wt% $Al_{2}$O$_{3}$-doped, 1000.angs.-thick ZnO deposited by r. f. magnetron sputtering. The optimum operating temperature of the sensor is 350.deg.C and the corresponding heater power is about 85mW. Excellent thermal insulation is achieved by the use of a double-layer structure of 0.2.mu.m -thick silicon nitride and 1.4.mu.m-thick phosphosilicate glass(PSG) prepared by low pressure chemical vapor deposition(LPCVD) and atmospheric pressure chemical vapor deposition(APCVD), respectively. The sensors are mechanically stable enough to endure at least 43, 200 heat cycles between room temperature and 350.deg. C.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.275-275
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• 2008

This paper describe the fabrication of a Pd/polycrystalline 3C-SiC schottky diode and its characteristics, in which the polycrystalline 3C-SiC layer and Pd Schottky contact were deposited by using APCVD and sputter, respectively. Crystalline quality, uniformity, and preferred orientations of the Pd thin film were evaluated by SEM and XRD, respectively. Pd/poly 3C-SiC Schottky diodes were fabricated and characterized by I-V and C-V measurements. Its electric current density Js and barrier height voltage were measured as $2\times10^{-3}$ A/$cm^2$ and 0.58 eV, respectively. These devices were operated until about $400^{\circ}C$. Therefore, from these results, Pd/poly 3C-SiC Schottky devices have very high potential for high temperature chemical sensor applications.

• 대한전자공학회논문지
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• 제18권1호
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• pp.35-40
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• 1981

분무법(spray method), 화학증착법(chemical vapor deposition method) 및 진공도착법 등을 사용하여 SRO2, SROr-ZnO 및 ZnO 박막가스 검지소자를 제조하였다. 제된된 소자들은 CO 및 SO2 등 유독가스를 포함한 여러 가지 가스에 대해 민감한 반응을 나타내었다. 박막가스 검지소자가 각종 가스와 접촉할 때 생기는 전기시도도의 변화는 이들 가스의 표면흡착에 의한 캐리어밀도의 변화에 기인하는 것으로 사료된다. 아울러 제조된 청막소자의 전기부도도는 소자 주위에 유지되는 기력에 따라 크게 달라짐을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.113.1-113.1
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• 2014

Surface-enhanced Raman scattering (SERS) has long been projected as a powerful analytical technique for chemical and biological sensing applications. Pairing with portable Raman spectrometers makes the technique extremely appealing as real-time sensors for field application. However, the lack of reliable, uniform, low cost and ease-of-use SERS enhancement structures has prevented the wide adoption of this technique for general applications. We have discovered a novel hybrid structure based on the high-density and uniform arrays of gold nanofingers over a large surface area for SERS applications. The nanofingers are flexible and their tips can be brought together to trap molecules to mimic the biological system. We report here a rapid, simple, low-cost, and sensitive method of detecting trace level of food contaminants by using nanofinger chips based on portable SERS technique. We also present here the characterization of surface reaction of target molecules with our gold nanofinger substrates and the effect of nanofinger closing towards SERS performance. This new type of nano-structures can potentially revolutionize the medical and biologic research by providing a novel way to capture, localize, manipulate, and interrogate biological molecules with unprecedented capabilities.

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.291-294
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• 2003

A highly interferent-resistive membrane, poly-5-amino-1-naphthol (poly-5A1N), underlied beneath enzymeembedded poly-1,3-phenylendiamine (poly-m-PD) network for miniturized continuous monitoring glucose sensors. The enzyme layer was prepared from a mixed solution of glucose oxidase (GOx) and m-PD monomer by simple electrolysis. The mass change of poly-5A1N was monitored by electrochemical quartz crystal microbalance (EQCM) in situ and the corresponding thickness was measured. Successive electropolymerization of poly-5A1N and poly-m-PD create a several tens nm-thick bilayer showing excellent selectivity for $H_2O_2$ and low activity loss of immobilized enzymes.

• 한국전기전자재료학회논문지
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• 제22권12호
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• pp.1089-1094
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• 2009

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. In this paper, networks of Multi-walled carbon nanotube (MWCNT) materials were investigated as resistive gas sensors for ethanol ($C_2H_5OH$) detection. Sensor films were fabricated by air spray method for the multi-walled CNTs solution on glass substrates. Sensors were characterized by resistance measurements in the sensing system, in order to find the optimum detection properties for the ethanol gas molecular. The film that was sprayed with the MWCNT dispersion for 60 see, was 300 nm thick. And the electric resistivity is $2{\times}10^{-2}\;{\Omega\cdot}cm$. Also, the sensitivity and the linearity of MWVNT sensor for ethanol gas are 0.389 %/sec and 17.541 %/FS, respectively. The MWCNT film was excellent in the response for the ethanol gas molecules and its reaction speed was very fast, which could be using as ethanol gas sensor. The conductance of the fabricated sensors decreases when the sensors are exposed to ethanol gas.

• Journal of Electrochemical Science and Technology
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• 제7권4호
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• pp.277-285
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• 2016

There is a growing demand for simple, cost-effective, and accurate analytical tools to determine the concentrations of biological and environmental compounds. In this study, a stable electroactive thin film of cobalt hexacyanoferrate (Cohcf) was prepared as an in situ chemical precipitant using electrostatic adsorption of $Co^{2+}$ on a silicate sol-gel matrix (SSG)-modified indium tin oxide electrode pre-adsorbed with $[Fe(CN)_6]^{3-}$ ions. The modified electrode was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical techniques. Electrocatalytic oxidation of hydrazine on the modified electrode was studied. An electrochemical sensor for hydrazine was constructed on the SSG-Cohcf-modified electrode. The oxidation peak currents showed a linear relationship with the hydrazine concentration. This study provides insight into the in situ growth and stability behavior of Cohcf nanostructures and has implications for the design and development of advanced electrode materials for fuel cells and sensor applications.

• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.290-296
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• 2011

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. In this paper, networks of Multi-walled carbon nanotube (MWCNT) materials were investigated as a resistive gas sensors for the $H_2$ gas detection. Sensor films were fabricated by the air spray method using the multi-walled CNTs dispersion solution on the glass substrates cured with plasma and nitrocellulose. Sensors were characterized by the resistance measurements in the self-fabricated oven in order to find the optimum detection properties for the hydrogen gas molecular. The sensitivity and the linearity of the MWVNT sensors using the glass substrate cured with plasma for the $H_2$ gas concentration of 0.06~0.6 ppm are 0.013~0.097%/sec and 0.131~0.959%FS, respectively. The MWCNT film was excellent in the response for the hydrogen gas moleculars and its reaction speed was very fast, which could be using as hydrogen gas sensor. The resistance of the fabricated sensors decreases when the sensors are exposed to $H_2$ gas.

• 센서학회지
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• 제22권4호
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• pp.239-243
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• 2013

Several methods are available to measure the oxidation of edible oils, such as their acid, peroxide, and anisidine values. However, these methods require large quantities of reagents and are time-consuming tasks. Therefore, a more convenient and time-saving way to measure the oxidation of edible oils is required. In this study, an edible oil-condition sensor was fabricated using single-walled nanotubes (SWNTs) made using the spray deposition method. SWNTs were dispersed in a dimethylformamide solution. The suspension was then sprayed using a spray gun onto a prefabricated Au/Ti electrode. To test the sensor, oxidized edible oils, each with a different acid value, were prepared. The SWNT sensors were immersed into these oxidized oils, and the resistance changes in the sensors were measured. We found that the conductivity of the sensors decreased as the oxidation level of the oil increased. In the case of the virgin oil, the resistance change ratio in the SWNT sensor S(%) = {[(Rf - Ri)]/Ri}(%) was more than 40% after immersion for 1 min. However, in the case of the oxidized oil, the resistance change ratio decreased to less than that of the response of the virgin oil. This result suggests that the change in the oil components induced by the oxidation process in edible oils is related to the conductivity change in the SWNT sensor.