• Transactions on Electrical and Electronic Materials
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• v.13 no.4
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• pp.165-170
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• 2012

One-dimensional, nanomaterial field effect transistors (FET) are promising sensors for bio-molecule detection applications. In this paper, we review fabrication and characteristics of 1-D nanomaterial FET type biosensors. Materials such as single wall carbon nanotubes, Si nanowires, metal oxide nanowires and nanotubes, and conducting polymer nanowires have been widely investigated for biosensors, because of their high sensitivity to bio-substances, with some capable of detecting a single biomolecule. In particular, we focus on three important aspects of biosensors: alignment of nanomaterials for biosensors, surface modification of the nanostructures, and electrical detection mechanism of the 1-D nanomaterial sensors.

• Particle and aerosol research
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• v.6 no.3
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• pp.131-138
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• 2010

Flexible electronics are the electronics on flexible substrates such as a plastic, fabric or paper, so that they can be folded or attached on any curved surfaces. They are currently recognized as one of the most innovating future technologies especially in the area of portable electronics. The conventional vacuum deposition and photolithographic patterning methods are well developed for inorganic microelectronics. However, flexible polymer substrates are generally chemically incompatible with resists, etchants and developers and high temperature processes used in conventional integrated circuit processing. Additionally, conventional processes are time consuming, very expensive and not environmentally friendly. Therefore, there are strong needs for new materials and a novel processing scheme to realize flexible electronics. This paper introduces current research trends for flexible electronics based on (a) nanoparticles, and (b) novel processing schemes: nanomaterial based direct patterning methods to remove any conventional vacuum deposition and photolithography processes. Among the several unique nanomaterial characteristics, dramatic melting temperature depression (Tm, 3nm particle~$150^{\circ}C$) and strong light absorption can be exploited to reduce the processing temperature and to enhance the resolution. This opens a possibility of developing a cost effective, low temperature, high resolution and environmentally friendly approach in the high performance flexible electronics fabrication area.

• Journal of Powder Materials
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• v.29 no.6
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• pp.511-516
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• 2022

Electroless plating is widely utilized in engineering for the metallization of insulator substrates, including polymers, glass, and ceramics, without the need for the application of external potential. Homogeneous nucleation of metals requires the presence of Sn-Pd catalysts, which significantly reduce the activation energy of deposition. Therefore, rinsing conducted during Sn sensitization and Pd activation is a key variable for the formation of a uniform seed layer without the lack or excess of catalysts. Herein, we report the optimized rinsing process for the functionalization of Sn-Pd catalysts, which enables the uniform FeCo metallization of the glass fibers. Rinsing enables good deposition of the FeCo alloy because of the removal of excess catalysts from the glass fiber. Concurrently, excessive rinsing results in a complete removal of the Sn-Pd nucleus. Collectively, the comprehensive study of the proposed nanomaterial preparation and surface science show that the metallization of insulators is a promising technology for electronics, solar cells, catalysts, and mechanical parts.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.4
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• pp.218-227
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• 2015

A prerequisite for precise quantification of nanomaterials contained in environmental samples is to prepare suitable preservation conditions of samples. This study was initiated to suggest preservation conditions of aqueous samples for analyses of metal nanomaterials. Variation in the size of silver nanomaterial (cit-AgNP) was observed according to change in various conditions, such as pH, electrolyte concentration, temperature, nanomaterial concentration, and time. Aggregation of AgNP was characterized for each environmental condition, and finally proper preservation conditions of samples were proposed based on experimental results on AgNP aggregation. In addition, the preservation period of sample was computed by the doublet time of AgNP. The results indicate that the aggregation rate of cit-AgNP was close to 0 at the conditions of pH of ${\geq}7$, electrolyte ($Ca(NO_3)_2$) concentration of ${\leq}3mM$, temperature of $4^{\circ}C$, and cit-AgNP concentration of ${\leq}2mg/L$. Furthermore, the experimental results on doublet time of cit-AgNP suggest that maximum preservation period was evaluated to be 15.79~17.53 days when the concentration of 100 nm cit-AgNP is assumed to be $1{\mu}g/L$ which is considered as an environmentally-relevant concentration of engineered nanomaterials. Our results suggest that samples should be preserved at $4^{\circ}C$ and analyzed within 2 weeks.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.10.2-10.2
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• 2011

The design and synthesis of protein-like polymers is a fundamental challenge in materials science. A biomimetic approach is to explore the impact of monomer sequence on non-natural polymer structure and function. We present the aqueous self-assembly of two peptoid polymers into extremely thin two-dimensional (2D) crystalline sheets directed by periodic amphiphilicity, electrostatic recognition and aromatic interactions. Peptoids are sequence-specific, oligo-N-substituted glycine polymers designed to mimic the structure and functionality of proteins. Mixing a 1:1 ratio of two oppositely charged peptoid 36 mers of a specific sequence in aqueous solution results in the formation of giant, free-floating sheets with only 2.7 nm thickness. Direct visualization of aligned individual peptoid chains in the sheet structure was achieved using aberration-corrected transmission electron microscopy. Specific binding of a protein to ligand-functionalized sheets was also demonstrated. The synthetic flexibility and biocompatibility of peptoids provide a flexible and robust platform for integrating functionality into defined 2D nanostructures. In the later part of my talk, we describe the use of metal ions to construct two-dimensional hybrid films that have the ability to self-heal. Incubation of biomimetic peptoid polymers with specific divalent metal ions results in the spontaneous formation of uniform multilayers at the air-water interface. We anticipate that ease of synthesis and transfer of these two-dimensional materials may have many potential applications in catalysis, gas storage and sensing, optics, nanomaterial synthesis, and environmentally responsive scaffolds.

• Electronics and Telecommunications Trends
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• v.33 no.1
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• pp.123-130
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• 2018

Tactile sensors, which are commonly referred to as pressure and strain sensors, have been extensively investigated to meet the demands for attachable and wearable electronics for monitoring the health status or activity of human users. For this purpose, the introduction of two-dimensional (2D) materials such as graphene and transition metal dichalcogenides (TMDs) with high mechanical strength at the atomic scale is very suitable for tactile sensors applicable for use in human-friendly devices. In this paper, we examine a descriptive summary of a tactile sensor and review state-of- the-art research trends of 2D material-based tactile sensors in terms of the material and architecture. Finally, we propose a roadmap for future studies into advanced tactile sensors based on our ongoing research.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.10a
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• pp.88-89
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• 2011

The study on synthesis of carbon nanomaterials by H2 mixing in counterflow methane diffusion flames has been experimentally conducted. We have also investigated on effect of catalyst and temperature in flame. The counterflow flame was formed by many kind of gas (fuel side using $CH_4-H_2-N_2$ and oxidizer side $N_2-O_2$) and nitrogen shields discharge on each other side to cut off oxidizer of the atmosphere. Ferrocene was used as a metal catalyst for CNTs synthesis. substrate was used to deposit carbon nanomaterials and these were analyzed by FE-SEM. We could find that carbon nanotubes and many kind of carbon nano materials were formed in Cu wire substrate, through this experiment.

• Journal of Powder Materials
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• v.15 no.2
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• pp.114-118
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• 2008

Functional nanomaterial is expected to have improved capacities on various fields. Especially, metal nanoparticles dispersed in polymer matrix and metal nanofiber, one of the functional nanomaterials, are able to achieve improvement of property in the electric and other related fields. In this study, the fabrication of metal (Ag) nanoparticle dispersed nanofibers were attempted. The Ag nanoparticle dispersed polymer nanofiber and Ag nanofiber were fabricated by electrospinning method using electric force. First, PVP/$AgNO_3$ nanofibers were synthesized by electrospinning in $18{\sim}22kV$ voltage with the starting materials (Ag-nitrate) added polymer (PVP; poly (vinylpyrrolidone)). Then Ag nanoparticle dispersed polymer nanofibers were fabricated to reduce hydrogen reduction at $150^{\circ}C$ for 3hr. And Ag nanofibers were synthesized by the decomposited of PVP at $300{\sim}500^{\circ}C$ for 3hr. The nanofibers were analyzed by XRD, TGA, FE-SEM and TEM. The experimental results showed that the Ag nanofibers could be applied in many fields as an advanced material.

• Carbon letters
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• v.17 no.1
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• pp.18-28
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• 2016

Global warming is considered one of the great challenges of the twenty-first century. In order to reduce the ever-increasing amount of methane (CH₄) released into the atmosphere, and thus its impact on global climate change, CH₄ storage technologies are attracting significant research interest. CH₄ storage processes are attracting technological interest, and methane is being applied as an alternative fuel for vehicles. CH₄ storage involves many technologies, among which, adsorption processes such as processes using porous adsorbents are regarded as an important green and economic technology. It is very important to develop highly efficient adsorbents to realize techno-economic systems for CH₄ adsorption and storage. In this review, we summarize the nanomaterials being used for CH₄ adsorption, which are divided into non-carbonaceous (e.g., zeolites, metal-organic frameworks, and porous polymers) and carbonaceous materials (e.g., activated carbons, ordered porous carbons, and activated carbon fibers), with a focus on recent research.

• Ceramist
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• v.22 no.1
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• pp.36-55
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• 2019

Atomically thin two-dimensional (2D) nanomaterials, including transition metal dichalcogenides (TMDs), graphene, boron nitride, and black phosphorus, have opened up new opportunities for the next generation optoelectronics owing to their unique properties such as high absorbance coefficient, high carrier mobility, tunable band gap, strong light-matter interaction, and flexibility. In this review, photodetectors based on 2D nanomaterials are classified with respect to critical element technology (e.g., active channel, contact, interface, and passivation). We discuss key ideas for improving the performance of the 2D photodetectors. In addition, figure-of-merits (responsivity, detectivity, response speed, and wavelength spectrum range) are compared to evaluate the performance of diverse 2D photodetectors. In order to achieve highly reliable 2D photodetectors, in-depth studies on material synthesis, device structure, and integration process are still essential. We hope that this review article is able to render the inspiration for the breakthrough of the 2D photodetector research field.