• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.31-34
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• 1995

The NO$_2$ gas-deteotion characteristics were investigated using the functional organic Langmuir-Blodgett(LB) files of Dilithium phthalocyanines(Li$_2$Pc). The optimum conditions for a film deposition were obtained through a study of $\pi$-A isotherms, and the deposited film status was confirmed by the ellipsometry measurements. A propel number of layers for the gas-detection was proved to be 9 layers from a measurement of a measurement of change in the electrical conductivities when the films were exposed to the 200 ppm of the NO$_2$ gases. A response time, recovery time, and reproducibility were also studied. A proper temperature which was able to activate gas interaction between NO$_2$ gases and Li$_2$Pc LB films was around 150$^{\circ}C$ judging from the electrical conductivities in a temperature range of 20 to 200$^{\circ}C$. It was found that at 150\ulcorner there are increments of electrical conductivities by 65 tines, 30 seconds of response time and 60 seconds of recovery tine when the filmswere exposed to the gasses.

• Journal of the Korean Applied Science and Technology
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• v.13 no.3
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• pp.105-109
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• 1996

It is well known that the metallo- phthalocyanine (MPcs) are sensitive to toxic gaseous molecules such as $NO_2$ and also chemically and thermally stable, Therefore, lots of MPcs have been studied for the potential chemical sensor for $NO_2$ gas using quartz crystal microbalance(QCM) or electrical conductivity. In this study, ultra-thin films of octa(2-ethylhexyloxy)copper-phthalocyanine were prepared by Langmuir-Blodgett method and characterized by using UV-VIS absortion spectroscopy and ellipsometry. Transfer condition, and characterization of LB films were investigated and preliminary results of current-voltage(I-V) characteristics of these films exposed to $NO_2$ gas as a function of film thickness and temperature were discussed.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.231-233
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• 1994

We have studied a properly of N-docosyl pyridinium(TCNQ) Langmuir-Blodgett film at room temperature with the $NO_2$ gas-detection characteristics. As a result, we have found that their conductivities were increased by 6 times at 5 layers(about $250{\AA}$ thickness) LB film. However, their reproducibility was not able to be measured at room temperature. Therefore, we must find their working temperature which was able to activate gas-detection characteristics. The $NO_2$ gas response experiments under 200 ppm concentration in $50^{\circ}C$ show that :here are increment of electrical conductivity by 8 times and 100 seconds of response time, and 200 seconds of recovery times at $60^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.549-553
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• 1998

The structure and layer distribution of cadmium arachidate Langmuir-Blodgett film were analyzed by the small angle X-ray reflectivity measurements using synchrotron radiation. Y-to X type transition was ocurred during the 39th passage of deposition of cadmium arachidate. Based on the measurement of the consumed area of the monolayer, it was determined that about 27.5 layer was deposited. Using the synchrotron X-ray, the reflectivity profile of cadmium arachidate LB film over the wide range of grazing angle was obtained. The X-ray reflectivity profile was analyzed using the recursion formula. By fitting the location and dispersion of the subsidiary maxima between the Bragg peaks of the measured reflectivity profile with that of the calculated reflectivity profile, the average thickness and the distribution of layer thickness were evaluated. The genetic algorithm was adopted to the fitting of reflectivity profile to evaluate the optimum value of the number distribution of layer. Based on the morphology measurement with an atomic force microscopy (AFM), the domain structure and mean roughness of LB films were obtained. The mean roughness value calculated based on the number of layer distribution obtained from the measurement by AFM is consistent with that obtained from X-ray reflectivity analysis.

• Food Engineering Progress
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• v.14 no.1
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• pp.49-53
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• 2010

Surface plasmon resonance (SPR) which is utilized in thin film refractometry-based sensors has been concerned on measurement of physical, chemical and biological quantities because of its high sensitivity and label-free feature. In this paper, an application of SPR to detection of alcohol content in wine and liquor was investigated. The result showed that SPR sensor had high potential to evaluate alcohol content. Nevertheless, food industry may need SPR sensor with higher sensitivity. Herein, we introduced a nano-technique into fabrication of SPR chip to enhance SPR sensitivity. Using Langmuir-Blodgett (LB) method, gold film with nano-structured surface was devised. In order to make a new SPR chip, firstly, a single layer of nano-scaled silica particles adhered to plain surface of gold film. Thereafter, gold was deposited on the template by an e-beam evaporator. Finally, the nano-structured surface with basin-like shape was obtained after removing the silica particles by sonication. In this study, two types of silica particles, or 130 nm and 300 nm, were used as template beads and sensitivity of the new SPR chip was tested with ethanol solution, respectively. Applying the new developed SPR sensor to a model food of alcoholic beverage, the sensitivity showed improvement of 95% over the conventional one.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.3
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• pp.34-40
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• 1993

전기전자산업에 유기분자집합체에 대한 전자 device적 기능을 갖게 하는 초전막형성 기술의 하나로서 LB막이 이용되게 된다. 10여년전에 만들어 대기중에 방치되었던 Langmuir Blodgett(LB) 초전막 시료에 대해서 MIM구조소자에 전하가 발생하는 특성을 검토하였다.그 결과 LB막이 무극성일 때는 상하부전극을 동일 금속으로 하면 전압이 발생하지 않고, 서로 다른 금속전극으로 할 때는 전압이 발생하였는데 양전극금속의 일함수값의 차가 클수록 발생전압이 높았고 LB막이 유극성일때는 동일 전극이라도 전압이 발생하였다.따라서 LB초전막의 MIM 소자에서 발생하는 전하는 단순한 화학작용에 의한 것이 아니고양전극 금속의 일함수와 극성에 관계가 있다고 생각된다.

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.81-87
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• 1995

A novel biomaterial capable of incorporating biotinylated biomolecule has been synthesized. Our strategy is to biotinylate one-dimensional electroactive polymers and use a bridging streptavidin protein on Langmuir-Blodgett (LB) organized films. These copolymers are derivatized with long alkyl chains and biotin moieties to bind, respectively, to the hydrophobic surface and the biotinylated species, through the biotin and streptavidin complexation. We utilize the polymer assembly approach to attach a signal transducing biomolecule biotinylated phycoerythrin (B-PE) into this novel biomaterial by binding the unoccupied biotin binding sites on the bound streptavidin (4 sites total). The pressure-area isotherm of the protein injected monolayer showed area expansion. A characteristic fluorescent emission peak at 576nm was detected from the monolayer transferred onto a solid substrate. These observations demonstrated the promise of the organized thin polymer assemblies for their application to the sensor system.

• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.224-231
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• 2009

Techniques measuring Maxwell displacement current (MDC) and LB films surface measuring technique have been applied to the study of monolayers of polyamic acid containing azobenzene. MDCs was generated from monolayers on the water surface by monolayer compression and expansion. It was generated when the area per molecule was about $103{\AA}^2\;and\;78{\AA}^2$ just before the initial rise of the surface pressure during the 1st and 2nd mixed monolayer compressions cycle, respectively. It was the maximum of MDCs appeared at the molecular area just before the initial rise of surface pressure in compression cycles, and we have found that the increase of aggregations causes the noticeable increase of the surface roughness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.351-354
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• 2001

We fabricated organic electroluminescent(EL) devices with mixed emitting layer of poly (N- vinylcarbazole) ( PVK) , 2,5-bis (5-tert-butyl -2- benzoxaBoly) thiophene ( BBOT) , N,N-diphenyl-N,N- (3-methyphenyl) -1,1-biphenyl-4, 4-thiamine(TPD) and poly(3-hexylthiophene) (P3HT) deposited by LB(Langumuir-Boldgett) method. From the AFM(atomic force microscope) images, the monolayer containing 30% of AA(arachidic acid) showed a roughness value of 28$\AA$. In the voltage-current characteristics of ITO/Emitting layer/BBOT/LiF/A1 devices, current density much smaller than that of the spin-coated devices having a same thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.277-280
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• 1997

It is important to investigate the molecular arrangement and the orientational distribution in the study of LB films. Polarized UV/visible absorption spectra make it possible to reveal the molecular arrangement and the orientational distribution. It is clarified that the PAAS LB films have specific directions in the molecular arrangement and the orientational distribution, which art different in intensity corresponding to the surface pressure. Unpolarized UV/visible absorption spectra reveal that the surface pressure is proportional to the finn thickness and is related to the molecular orientation. Current-Voltage(I-V) measurements provide that the current decreases as the surface pressure increases and there are certain phenomena called switching phenomena. Switching effort indicates that the current flows in high conductivity during on-state and suddenly decreases into low conductivity during off-state.