• Journal of Surface Science and Engineering
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• v.57 no.4
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• pp.265-273
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• 2024

An amperometric sensor for measuring indole-3-acetic acid (IAA) was studied based on a screen-printed carbon electrode (SPCE) coated with a reduced graphene oxide composite electrocatalyst. The PEI-GO dispersion is uniformly formed through a nucleophilic substitution reaction between the active amine group of Polyethyleneimine (PEI) and the epoxide group exposed on the surface of graphene oxide. And The 3-dimensional PEI-rGO AG (Polyethyleneimine-reduced graphene oxide aerogel) complex was easily prepared through simple heat treatment of the combined PEI-GO dispersion. The proposed composite catalyst electrode, PEI-rGO AG/SPCE, showed a two linear relationship in the low and high concentrations in IAA detection, and the linear equation was I_pa = 0.2883C + 0.0883 (R²=0.9230) at low concentration and Ipa = 0.00464C + 0.6623 (R²=0.9894) at high concentration was proposed, and the detection limit was calculated to be 203.5nM±33.2nM. These results showed the applicability of the PEI-rGO AG composite catalyst as an electrode material for electrocatalysts for the detection of IAA.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.347.1-347.1
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• 2016

Screen printing is commonly used to form the electrode for crystalline silicon solar cells. However, it has caused high resistance and low aspect ratio, resulting in decrease of conversion efficiency. Accordingly, Ni/Cu/Ag plating method could be applied for crystalline silicon solar cells to reduce contact resistance. For Ni/Cu/Ag plating, laser ablation process is required to remove anti-reflection layers prior to the plating process, but laser ablation results in surface damage and then decrease of open-circuit voltage and cell efficiency. Another issue with plating process is ghost plating. Ghost plating occurred in the non-metallized region, resulting from pin-hole in anti-reflection layer. In this paper, we investigated the effect of Ni/Cu/Ag plating on the electrical properties, compared to screen printing method. In addition, phosphoric acid layer was spin-coated prior to laser ablation to minimize emitter damage by the laser. Phosphorous elements in phosphoric acid generated selective emitter throughout emitter layer during laser process. Then, KOH treatment was applied to remove surface damage by laser. At this step, amorphous silicon formed by laser ablation was recrystallized during firing process and remaining of amorphous silicon was removed by KOH treatment. As a result, electrical properties as Jsc, FF and efficiency were improved, but Voc was lower than screen printed solar cells because Voc was decreased due to surface damage by laser process. Accordingly, we expect that efficiency of solar cells could be improved by optimization of the process to remove surface damage.

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.467-472
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• 2002

Long Carbon Nanotubes(CNTs) were cut by diamond lapping film followed by observation using SEM. The paste was prepared by mixing shortened CNT powder, ${\alpha}$-terpineol used as a solvent, and ethylcellulose as a binder. This paste was deposited on glass substrate by screen printing and extruded by syringe. After screen printing, several post-treatments were performed to control the alignment of CNTs perpendicular to the substrate. The deposited CNTs were scratched by sand paper or diamond lapping film. It was also treated by attachment followed by an immediate detachment using the adhesive tape. SEM observation indicates that excellent vertical alignment of CNTs could be achieved by simple post-treatments from the screen printed-CNTs paste. Similar alignment of CNTs is also observed in the as-extruded CNTs paste.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1806-1809
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• 2008

Study that form micro pattern by direct ink jet printing method is getting attention recently. Direct ink jet printing spout fine droplet including nano metal particle by force or air pressure. There is reason which ink jet printing method is profitable especially in a various micro-patterning technology. It can embody patterns directly without complex process such as mask manufacture or screen-printing for existent lithography. In this study, research of a technology that ejects fine droplet form of Pico liter and forms metal micro pattern was carried with inkjet head of piezoelectricity drive system. Droplet established pattern while ejecting consecutively and move on the surface at the fixed speed. Patterns formed in ink are mixed with organic solvent and polymer that act as binder. So added thermal hardening process after evaporate organic solvent at isothermal after printing. I executed high frequency special quality estimation of CPW transmission line to confirm electrical property of manufactured circuit board. We tried a large area printing to confirm application possibility of an ink jet technology.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.20.2-20.2
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• 2010

Recently inkjet printing technology has been developed in the areas of low cost fabrication in environmentally friendly manufacturing processes. Although inkjet printing requires the interdisciplinary researches including development of materials, manufacturing processes and printing equipment and peripherals, manufacturing a printhead is still core of inkjet technology. In this study, a piezoelectric driven DOD (drop on demand) inkjet printhead has been fabricated on three layers of the silicon wafer in MEMS Technology because of its chemical resistance to industrial inks, strong mechanical properties and dimensional accuracy to meet the drop volume uniformity in printed electronics and display industries. The flow passage, filter and nozzles are precisely etched on the layers of the silicon wafers and assembled through silicon fusion bonding without additional adhesives. The piezoelectric is screen-printed on the top the pressure chamber and the nozzle plate surface is treated with non-wetting coating for jetting fluids. Printheads with nozzle number of 16 to 256 have been developed to get the drop volume range from 5 pL to 80 pL in various industrial applications. Currently our printheads are successfully utilized to fabricating color-filters and PI alignment layers in LCD Flat Panel Display and legend marking for PCB in Samsung Electronics.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.10
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• pp.1153-1158
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• 2011

Roll-to-roll process is an emerging mass production method for printed and flexible electronics such as touch screen panel, RFID tag, thin film solar cell, and flexible display due to its high throughput. High precision in printing and coating is required to apply functional materials onto substrate. For such reason, every part of the roll-to-roll equipment needs to be precisely fabricated and to retain its precision under regular operation. In this article, the precision of cantilever type idler roller and a novel method to mitigate its deflection under web tension loading are discussed and the method is verified using both the numerical and the experimental works. The proposed method improves the structural rigidity of cantilever type roller whose advantages, such as low capital cost and high web path configurability, are maintained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.6
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• pp.477-480
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• 2010

In this study, we fabricate 3 wt% $Li_2CO_3$ doped $(Ba,Sr)TiO_3$ thick films on the Ag/Pd bottom electrode printed $Al_2O_3$ substrates for the LTCCs (low temperature co-fired ceramics) applications. From the X-ray diffraction analysis, 3 wt% $Li_2CO_3$ doped BST thick films on the Ag/Pd printed $Al_2O_3$ substrates, which sintered at $900^{\circ}C$, showed perovskite structure without any pyro phase. The dielectric properties of 3 wt% $Li_2CO_3$ doped BST thick films are measured from 1 kHz to 1 MHz. To investigate the electrical properties of 3 wt% $Li_2CO_3$ doped BST thick films, we employ the impedance spectroscopy. The complex impedance of 3 wt% $Li_2CO_3$ doped BST thick films are measured from 20 Hz to 1 MHz at the various temperatures.

• The Research Journal of the Costume Culture
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• v.15 no.6
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• pp.1053-1062
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• 2007

This study purposed to restructure representative traditional patterns formatively, manufacture actual cultural products with traditional dyeing technique using persimmon, and commercialize the results of the research. Traditionally in Korea, the dying of natural fiber such as cotton, flax and silk with persimmon was called Galmul dyeing, and clothes made through Galmul dyeing were called Galot. Galot was very useful because it is strong, does not pick up dirt easily, dries easily, and is cool in summer. In addition, cloth dyed with persimmon becomes stiff, so it does not need to be starched or ironed after washing. Moreover, it does not transmit heat under direct rays and is highly air-permeable, so it is cool and useful for standing the heat. In this study, we used traditional persimmon dyeing technique, printing traditional patterns fit for contemporary people's aesthetic sense not through dip-dying but through printing. When persimmon dyeing is used in expressing patterns, it produces not only visual effect but also embossing effect due to the characteristic of persimmon that makes printed patterns stiff, so we can obtain unique texture distinguished from other printing methods. We chose seven motive patterns, which were lotus pattern symbolizing eternal life, peony pattern symbolizing wealth and rank and prosperity, character Su(壽) pattern widely used as a symbol of health, bird and cloud pattern in the Goryeo Dynasty, Sahapyeoeuisohwa(四合如意小花) pattern printed on brocade in the Goryeo Dynasty, lattice pattern, cloth pattern on wall paintings from the Period of the Three Kingdoms. From each pattern chosen as a motive was extracted unit patterns and the original pattern was restored using Adobe Illustrator. Restored patterns were restructured to be applied to cultural products fit for contemporary formative sense. Fabrics used in dyeing were cotton, linen, ramie, silk, and polyester. Although the same persimmon dyeing was applied, we produced different feelings of patterns using various fabrics and in some cases gold and silver powder was added for the effect of gloss in addition to the embossing of patterns. Using printed fabrics we manufactured tea pads, place mats, cushions, wrapping cloth for gifts, wallet, lampshades.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.3025-3029
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• 2014

To realize copper-based electrode materials for printed electronics applications, it is necessary to improve the adhesion strength between conductive lines and the substrate. Here, we report the preparation of Cu pastes using (3-glycidoxypropyl) trimethoxysilane (GPTMS) prepolymer as an adhesion promoter (AP). The Cu pastes were screen-printed on glass and polyimide (PI) substrates and sintered at high temperatures (> $250^{\circ}C$) under a formic acid/$N_2$ environment. According to the adhesion strengths and electrical conductivities of the sintered Cu films, the optimized Cu paste was composed of 1.0 wt % GPTMS prepolymer, 83.6 wt % Cu powder and 15.4 wt % vehicle. After sintering at $400^{\circ}C$ on a glass substrate and $275^{\circ}C$ on a PI substrate, the Cu films showed the sheet resistances of $10.0m{\Omega}/sq$. and $5.2m{\Omega}/sq$., respectively. Furthermore, the sintered Cu films exhibit excellent adhesion properties according to the results of the ASTM-D3359 standard test.

• Analytical Science and Technology
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• v.20 no.5
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• pp.393-399
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• 2007

In principle, the blood galactose level may be determined conveniently with a strip-type biosensor similar to that for glucose. In this study, we describe the development of a disposable galactose biosensor strip for point-of-care testing. The sensor strip is constructed with screen-printed carbon paste electrode (SPCE) and sample amount (< $100{\mu}L$). The developed strip the galactose level in less than 90 s using bienzymatic system of galactose oxidase (GAO) and horseradish peroxidase (HRP). The effects of pH, mediator (1,1-ferrocenedimethanol) concentration, ratio of enzymes, and applied potential were determined preliminarily with glassy carbon electrodes, and optimized further with the strip-type electrodes. The sensor exhibits linear response in the range of $0{\sim}400{\mu}M$ ($r^2$ = 0.997, S/N = 3). Since a low working potential, in principle, the fabricated disposable galactose biosensor has -100 mV (vs. Ag/AgCl), it is applied for the detection of galactose, interfering responses from common interferents such as ascorbic acid, uric acid and acetaminophen could be minimized. The sensor has been used to determine the total galactose level in standard samples with satisfactory reproducibility (CV = 5 %).