• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.88-93
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• 2017

It is important to develop a simple method oftuning localized surface plasmon resonance(LSPR) properties, due to their numerous applications. In addition, the careful examination of the shape, size and combination of metal nanoparticles is useful for understanding the relation between the LSPR properties and metal nanostructures. This article describes the dependence of theLSPR properties on the arrays of metal nanoparticles obtained from a block copolymer(BCP) micellar thin film. Firstly, two different Au nanostructures, having a dot and ring shape, were fabricated using conventional block copolymer micelle lithography. Then, Ag was plated on the Au nanostructures through the silver mirror reaction technique to obtain Au/Ag bimetallic nanostructures. During the production of these metallic nanostructures, the processing factors, such as the pre-treatment by ethanol, silver mirror reaction time and removal or not of the BCP, were varied. Once the Au nanoparticles were synthesized, Ag was properly plated on the Au, providing two distinguishable characteristic plasmonic bands at around 525nm for Au and around 420nm for Ag, as confirmed bythe UV-vis measurements. However, when a small amount of Au seed nanoparticles, which accelerate the Ag plating speed,was formed by usinga block copolymer with a relatively highmolecular weight, all of the Au surfaces were fully covered by Ag during the silver mirror reaction, showing only the characteristic peak for Ag at around 420nm. The Ag plating technique on Au nanoparticles pre-synthesized from a block copolymer is useful to study the LSPR properties carefully.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.11-15
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• 2018

In this study, we deposited silver nanoparticles on the nanocone array structure which was fabricated by the UV nanoimprint process for optical signal amplification. The deposition of the silver nanoparticles was based on the evaporation behavior of the solution droplet according to wettability of surface and the deposition pattern changed from the center of the droplet to the edge depending on the difference of thermal energy. The optical property of silver nanoparticles that were deposited on imprinted nanohole patterns was simulated by the Finite difference time domain (FDTD) analysis method, and it was confirmed that energy was concentrated around the silver nanoparticle of the finally fabricated structure.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.346.1-346.1
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• 2016

본 연구에서는 열처리(Thermal Dewetting Process)와 빗각 증착(Oblique angle deposition)을 이용하여 비주기 서브파장 구조물을 마이크로 렌즈 형태의 유리 기판 상부에 제작하였다. 먼저 $2{\times}2cm2$ 크기의 유리 기판에 기존 리소그래피 공정으로 원기둥 형태의 감광액을 형성한다. 이후 Hot-plate로 $180^{\circ}C$에서 90초간 열을 가해 지름이 $20{\mu}m$인 반구형태로 변형시킨 뒤 반응성이온식각 공정을 진행하여 마이크로 렌즈를 제작한다. 렌즈의 표면에 나방 눈 구조를 형성하기 위해 전자빔 증착으로 15nm의 은 박막을 쌓은 뒤 $500^{\circ}C$에서 1분간 열처리 공정을 진행하였다. 열이 가해졌을 때 은 박막은 표면자유에너지를 최소화하기 위해 나노 크기의 덩어리진 입자 형태로 변화한다. 여기서 형성되는 나노입자의 크기가 렌즈 표면 중심에서 가장자리로 갈수록 작아진다는 것을 주사전자현미경을 통해 확인하였다. 증착 각도가 증가할수록 열처리 공정 후의 은 나노입자의 크기가 점점 작아진다는 것을 검증하기 위해 은 박막의 증착 각도를 $0^{\circ}$, $35^{\circ}$, $55^{\circ}$, $70^{\circ}$로 증착 후 열처리 공정을 진행하여 확인하였다. 비스듬하게 증착되어 형성된 박막은 다공형태로 낮은 밀도를 가지는데 이는 박막 두께 감소를 일으킨다. 따라서 증착 각도가 증가할수록 열처리 공정 후의 은 나노입자의 크기는 점점 작아진다. 이후 은 나노입자를 마스크로 하여 다시 반응성이온식각 공정을 진행하였으며 식각 후 나머지 은 나노입자들은 HNO3용액에서 1분간 처리하여 제거하였다. 제작된 구조물의 평균 직경과 크기는 각각 ~220nm 및 ~250nm인 것으로 확인하였다. 위와 같은 공정을 통해 다양한 크기를 가진 비주기 서브파장 구조물을 제작할 수 있다. 구조물의 주기가 파장 길이보다 짧을 경우 분산이 최소화되며 넓은 파장 대역에서 무반사 효과를 얻을 수 있다. 이 공정은 마스크를 통한 리소그래피의 한계를 극복할 수 있으며 여러 곡면형 표면에 적용가능한 장점이 있다. 또한 프리즘, 렌즈, 광섬유와 같은 광소자의 광투과율을 향상시키는데 이용될 수 있다.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.73-76
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• 2020

Silver nanowires (AgNWs) intrinsically possess high conductivity, ductility, and network structure percolated in a low density, which have led to many advanced applications of transparent and flexible electronics. Most of these applications require patterning of AgNWs, for which photolithographic and printing-based techniques have been widely used. However, several drawbacks such as high cost and complexity of the process disturb its practical application with patterning AgNWs. Herein, we propose a novel method for the patterning of AgNWs by employing UV-curable adhesive tape with a structure of liner/adhesive layer/polyolefin (PO) film and UV irradiation to simplify the process. First, the UV-curable adhesive tape was attached to AgNWs/polyurethane (PU), and then selectively exposed to UV irradiation by using a photomask. Subsequently, the UV-curable adhesive tape was peeled off and consequently AgNWs were patterned on PU substrate. This facile method is expected to be applicable to the fabrication of a variety of low-cost, shape-deformable transparent and wearable devices.

• Journal of Sericultural and Entomological Science
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• v.49 no.1
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• pp.24-27
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• 2007

Silkworm fed on the mulberry leaf mixed with silver nanoparticle to produce silver-nanoparticle embedded cocoon. Comparative analysis of silver content of cocoon shell, percentage of pupation and percentage of cocoon-shell weight showed that the optimum concentration and the feeding period of mulberry leaf mixed with silver nanoparticle were 500 ppm and the period from 3 day 5 instar to mounting of silkworm. The silver content of cocoon was observed variously by silkworm breedings. C212 variety makes pale yellow cocoon with the highest silver content(69%). Using the scanning electron microscope, we showed that the size of silver nanoparticles in silk was observed from 26.98 to 99.81nm. Silver-nanoparticle embedded silk is expected to use as high valuable application owing to the different functional properties including antibiotic characteristics and mechanical and electronic properties. The applicable fields expected is antistatic and/or electronic products with biological degradable natural materials.

• Journal of the Korean Ceramic Society
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• v.41 no.10 s.269
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• pp.788-791
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• 2004

We have studied the fabrication of silver micro lines using the silver nano sol on ITO substrate by an ink-jet method. The average particles size of $10wt\%$ silver nano sol synthesized with polyelectrolytes was smaller than 10 nm. The pattern formation of silver nano sol on the substrate closely related with the contact angle of the silver nano sol. The dot shaped of silver nano sol on bare ITO substrate was formed due to the high contact angle of silver nano sol. When ITO substrates was treated with 100 ppm polyethylenimine for silver nano sol patterning, fine silver micro lines of $60{\sim}100{\mu}m$ width was fabricated by ink-jet method.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.77-85
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• 2011

The antibacterial activities of silver nanoparticles (Ag-NPs) were studied with respect to Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli by observing the bacterial cells treated or not with Ag-NPs by FE-SEM as well as measuring the growth curves, formation of bactericidal ROS, protein leakage, and lactate dehydrogenase activity involved in the respiratory chain. Bacterial cells were treated with Ag-NPs powder, and the growth rates were investigated under varying concentrations of Ag-NPs, incubation times, incubation temperatures, and pHs. As a result, S. aureus and E. coli were shown to be substantially inhibited by Ag-NPs, and the antibacterial activity of Ag-NPs did not fluctuate with temperature or pH. These results suggest that Ag-NPs could be used as an effective antibacterial material.

• Journal of Life Science
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• v.28 no.11
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• pp.1354-1360
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• 2018

The aim of this study was to develop a simple, environmentally friendly synthesis of silver nanoparticles (SNPs) without the use of chemical reducing agents by exploiting the extracellular synthesis of SNPs in a culture supernatant of Bacillus thuringiensis CH3. Addition of 5 mM $AgNO_3$ to the culture supernatant at a ratio of 1:1 caused a change in the maximum absorbance at 418 nm corresponding to the surface plasmon resonance of the SNPs. Synthesis of SNPs occurred within 8 hr and reached a maximum at 40-48 hr. The structural characteristics of the synthesized SNPs were investigated by various instrumental analysis. FESEM observations showed the formation of well-dispersed spherical SNPs, and the presence of silver was confirmed by EDS analysis. The X-ray diffraction spectrum indicated that the SNPs had a face-centered cubic crystal lattice. The average SNP size, calculated using DLS, was about 51.3 nm and ranged from 19 to 110 nm. The synthesized SNPs exhibited a broad spectrum of antimicrobial activity against a variety of pathogenic Gram-positive and Gram-negative bacteria and yeasts. The highest antimicrobial activity was observed against C. albicans, a human pathogenic yeast. The FESEM observations determined that the antimicrobial activity of the SNPs was due to destruction of the cell surface, cytoplasmic leakage, and finally cell lysis. This study suggests that B. thuringiensis CH3 is a potential candidate for efficient synthesis of SNPs, and that these SNPs have potential uses in a variety of pharmaceutical applications.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.12
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• pp.1873-1882
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• 2009

Hospital patient clothing material was treated with a mixture of chitosan in order to enhance functionality, such as the durability and dimensional stability of the cotton fabric used. Chitosan is a natural polymer with excellent biocompatibility, however there is a deteriorating adherence efficiency. The addition of a nanosilver colloidal solution in accordance with a prescribed ratio can further increase the performance of chitosan. Changes in the structural characteristics and physical properties of the chitosan/nanosilver treated fabric were observed in a comparison with fabric treated only with chitosan. The add-on ratio increased when the mixing ratio of nanosilver colloidal solution was higher; however, the crystalline structure of the treated fabric remains similar. In the case of CH3/NS1 treated fabric (where the mixing ratio of chitosan and nanosilver solution was 3:1) the K/S value, whiteness index, wet tensile strength, and wrinkle recovery angle were superior. The dimension stability, pilling resistance, and abrasion resistance of the fabric treated with a mixed solution increased in comparison to the fabric treated only with chitosan. The chitosan/nanosilver treated cotton fabric used for patient clothing material has excellent physical properties.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1553-1560
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• 2021

We have confirmed that optimized transmittance and surface resistance by electrospinning time, also the fabricated transparent electrode composed of silver nanofiber with excellent electrical, optical and mechanical performances is showed applicability to next generation flexible displays such as solar cells, displays, and touch screens. → We have confirmed the optimized transmittance and surface resistance by electrospinning time Also the fabricated transparent electrode composed of silver nanofiber with excellent electrical, optical and mechanical performances showed applicability to next generation flexible displays such as solar cells, displays, and touch screens.