• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.287-291
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• 2004

A capacitive type humidity sensor has been fabricated using a polyimide film without hydrophobic elements and its characteristics has been evaluated for hermeticity measurement of micro packages. For a highly sensitive humidity sensor, a polyimide film without hydrophobic elements has been synthesized and used instead of using a commercial one in which 7 group elements such as fluorine or chlorine are included. Sensitivity, stability and hysteresis has been performed to characterize the fabricated sensors. The sensitivity defined as normalized percent capacitance change was 0.3751%RH and hysteresis was 0.77% in the range of 10%RH to 90%RH. Maximum deviation from the average capacitance measured for 120 minutes at 50%RH was 0.25%. The proposed humidity sensor can be used for hermeticity measurement of micro packages.

• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.20-23
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• 2013

When applying superconducting wire to power machines, an investigation needs to be carried out on the characteristics of wire phase changes in connection with the insulating layer. This study examined trends in the increase of the wire's resistance and the characteristics of its recovery from quenching by a current-applied cycle at temperatures of 90 K, 180 K, and 250 K. The procedure was conducted based on the thickness and presence (or absence) of the insulating wire layers. To achieve this, YBCO thin-film wires with the same critical temperatures were prepared with copper and stainless steel stabilizing layers. At levels (-one, three, and five-), with superior performance, polyimide pressure-sensitive adhesive tape was attached to the wires at a very low temperature. The eight prepared test samples were wound around the linear frames. The wire's voltage and current created from the phase change characteristics were measured at the wire's prescribed temperature, using the four-point probe method. The wire's resistance and recovery characteristics were examined for each cycle at temperatures of 90 K, 180 K, and 250 K.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.11
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• pp.705-709
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• 2017

Effective surface area and morphology of a sensitive thin film are important factors for its applications in sensor systems for the analysis of physical properties. In this study, we investigated the morphologies, electrochemical properties, and applicability of zinc oxide multilayer thin films fabricated by electrodeposition and annealing. The microstructure and electrochemical properties of the zinc oxide films were dependent on temperature and applied voltage. The best characteristics were obtained at an applied voltage of -1.4 V and a temperature of $50^{\circ}C$. The morphologies also changed upon annealing. The results suggest that the zinc oxide films fabricated by electrodeposition and annealing can be applied as various sensor materials.

• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.52-58
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• 2004

Magneto-Impedance(MI) sensor is a highly sensitive sensor, which was able to detect a weak geomagnetic field. It also has a merit to be able to build in the low power system. In this study, their magnetic permeability and anisotropy field(H$\sub$k/) as a function of some different thickness of sputtered amorphous CoZrNb films with zero-magnetostriction and soft magnetic property are investigated. In order to make a uniaxial anisotropy, film was subjected to the post annealing in a static magnetic field with 1KOe intensity at 250, 300, and 320$^{\circ}C$ respectively for 2 hours. Magnetic properties of films are measured by using a M-H loop tracer. Magnetic permeability of a film is measured over the frequency range from 1 ㎒ to 750㎒. By thickening a CoZrNb film relatively, magnetic permeability and impedance are examine to design the. MI sensor which drives at 50㎒, and thereof fabricated the MI sensor which drives at the 50㎒.

• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.229-232
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• 2007

An amperometric immunosensor for the determination of rabbit IgG is proposed. The immunoassay utilizes a screen-printed carbon electrode on which osmium redox polymer is electrodeposited. This immunoassay detects 0.1 ng/ml of rabbit IgG, which is ${\sim}10^2$ fold higher than the most sensitive enzyme amplified amperometric immunoassay. The assay utilizes a screen-printed carbon electrode which was pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a rabbit IgG. The rabbit IgG in the electron conducting film conjugates captures, when present, the anti-rabbit IgG. The captured anti-rabbit-IgG is labeled with horseradish peroxidase (HRP) which catalyzes the two-electron reduction of $H_2O_2$ to water. Because the redox hydrogel electrically connects HRP reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electro-catalytic for the reduction of $H_2O_2$ to $H_2O$ when the electrode is poised at 200 mV vs. Ag/AgCl.

• Textile Coloration and Finishing
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• v.19 no.4
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• pp.10-17
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• 2007

Chitosan(CS) and cellulose acetate(CA) composite films were prepared using formic acid as a cosolvent by casting, solvent evaporating and neutralization method. This study examines if the blending method, which uses formic acid as a cosolvent is efficient in improving the mechanical properties of CS film, especially wet strength and elongation. Formic acid is an effective cosolvent for the blend of CS and CA. Under wet condition, tensile strength and elongation of the composite films were obviously higher than those of the films made from pure CS. FTIR, DSC, and X-ray diffraction showed that the composite films exhibit a high level of compatibility and that strong interaction between the CS and CA was caused by intermolecular hydrogen bonding. The affinity series of composite film to transition metal ions are Cu(II) > Cd(II) > Cr(III). The adsorption of Cu((II) ion was shown to be highly pH sensitive.

• Journal of the Korean Ceramic Society
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• v.34 no.10
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• pp.1021-1026
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• 1997

RuO2 thin film has reasonably good conductivity and stiffness and it is thought to substitute for the cantilever beam made up of Pt and Si3N4 double layers in microactuators. Therefore, anisotopic Si etching was performed using RuO2 thin film as a mask layer in 25 wt. % TMAH water solution. In the etching temperature ranging from 6$0^{\circ}C$ to 75$^{\circ}C$, the etch rates of all the crystallographic directions increased linearly as the etching temperature increased. The etch rate ratio(selectivity) of [111]/[100] which varied from 0.08 to 0.14, was not sensitive to temperature. The activation energies for [110] direction, [100] direction and [111] direction were 0.50, 0.66 and 1.04eV, respectively. RuO2 cantilever beam with a clean surface was formed at the etching temperatures of 6$0^{\circ}C$ and $65^{\circ}C$. But the damages due to formation of pin holes on RuO2 surface were observed beyond 7$0^{\circ}C$. The tensile stress of RuO2 thin films caused the cantilever bending upward. As a result, it was demonstrated that the formation of conducting oxide RuO2 cantilever beam which can replace the role of an electrode and supporting layer could be possible by TMAH solution.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3123-3127
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• 2010

A highly sensitive electrochemical detection method for dopamine (DA) has been developed by relying on a multiwalled carbon nanotube (CNT)-sol-gel titania-Nafion composite film modified glassy carbon (GC) electrode. The CNT-titania-Nafion/GC electrode exhibited excellent electrocatalytic activity towards DA. Therefore, the CNT-titania-Nafion/GC electrode showed improved voltammetric and amperometric responses for DA compared to those obtained with both titania-Nafion/GC and Nafion/GC electrodes. The CNT-titania-Nafion/GC electrode gave a linear response ($R^2$ = 0.999) for DA from $0.5\;{\mu}M$ to 0.5 mM with a detection limit (S/N = 3) of $0.1\;{\mu}M$ and a good sensitivity of 150 mA/M while other electrodes such as CNT-Nafion/GC, titania-Nafion/GC, and a bare GC gave a sensitivity of 89, 39, and 36 mA/M, respectively. Besides, the CNT-titania-Nafion/GC electrode displayed very fast response time within 2 s. The modified electrode showed good selectivity against ascorbic acid. The modified electrode showed good stability and reproducibility. The CNT-titania-Nafion/GC electrode was applied to the determination of DA in urine and serum samples.

• The Korean Journal of Ceramics
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• v.2 no.2
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• pp.89-94
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• 1996

Aluminum and zinc titanium silicate sol-gel films were fabricated for application of waveguide and the effect of additions of ZnO and $Al_2O_3$ to binary titanium silicate films was investigated. During firing, the films are densified as they shrunk and their refractive index increases in the range of 1.58-1.83 depending on the film composition. The attenuation of the waveguides is not sensitive to changes in composition except for zinc titanium silicate waveguides which have substantially higher attenuation. However, the increase in the attenuation with aging of the waveguides depend upon the composition of waveuides. The addition $Al_2O_3$ or the reduced $SiO_2$ content in the composition appears to slow the deterioration of the waveguides due to the formation of more stable bonds and increased acidity on the film surface. Also, the wavelength dependence of the attenuation of the waveguides varies with composition. The attenuation of the waveguides except for the $65SiO_2{\cdot}35TiO_2$ composition are not Rayleigh scatter limited, suggesting the absorption loss of the waveguides due to the effects of residual carbon and structural defects in the films.