Dae-Sup So

Electrical impedance properties of bulk carbon nanotube composites for chemical sensors and biosensors

Electrical impedance properties of bulk carbon nanotube (CNT) composite electrodes have been studied to develop chemical and biosensors. The CNTs embedded in composite electrodes were fabricated by means of traditional film casting and electrospun nanoweb. The morphology of the bulk CNT electrode was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Under the various amounts of buffer solution, electrical impedance of the composite electrodes was measured by means of LCR meter. It is generally known that electrical impedance measurement provides rapid and simple sensing mechanism. In this study, we found out that CNT bulk composite electrodes showed good sensing properties for chemical and bio sensors.

PU-Graphene Oxide Composite; Effect of Various Chain Extender on Properties

High integration of electronic chip not only improved the electronic device’s efficiency, but also left the need to stop emitting heat. Thermal interface material (TIM) has been proposed to solve this problem. Traditionally, a large amount of high thermal conductive materials (such as Cu, Al or AlN) was added for better thermal conductivity, which caused undesirable weight-increasing and property-sacrificing. Graphene has great thermal conductivity and mechanical properties. Furthermore, owing to its low density, it is possible to make a lot of TIM even with a small amount. Being composited with PU, it can be an enhanced thermal conductive adhesive. Otherwise, amine compound is considered to be applicable as both a chain extender of PU and a reducing agent of Graphene oxide (GO). In this work, we synthesized PU-GO composite by chemical reaction of NCO and GO. We examined the effects of various amine compounds on chemical and physical properties of GO and PU-GO composite. Adhesion and thermal properties were also studied.

High-quality ZnO nanowire arrays directly synthesized from Zn vapor deposition without catalyst

Vertically well-aligned ZnO nanowire (NW) arrays were synthesized directly on GaN/sapphire and Si substrate from Zn vapor deposition without catalysts. Experimental results showed that the number density, diameter, crystallinity and degree of the alignment of ZnO NWs depended strongly on both the substrate position and kind of the substrates used for the growth. The photoluminescence (PL) characteristics of the grown ZnO NW arrays exhibit a strong and sharp ultraviolet (UV) emission at 379 nm and a broad weak emission in the visible range, indicating that the obtained ZnO NWs have a high crystal quality with excellent optical properties. The as-grown ZnO NWs were characterized by using scanning electron microscopy (SEM), high resolution transmission electronic microscopy (HR-TEM), and X-ray diffraction (XRD).

Fabrication of single-phase tungsten carbide laminae from multi- walled carbon nanotubes using high direct current pulse

Single-phase tungsten carbide (WC) laminae were fabricated by reacting of multi-walled carbon nanotubes (MWCNTs) and tungsten trioxide using high direct current pulses. We confirmed that single-phase WC laminae are transformed from unzipped MWCNTs, and that they have a graphene layer structure. Therefore their thicknesses and widths are almost identical with those of transformed graphene layers from MWCNTs. A variety of characterizing techniques, such as a field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, has been used for the investigation of the characteristics of single-phase WC laminae.

Nanotechnology commercialization: World and Korean trends and their perspectives

Recently, nanotechnology(NT) commercialization is becoming increasingly emphasized. In this paper, we review the world and Korean trends of NT commercializations. Many products using the so-called classical benefits of NT which exploit the characteristics of the increased surface-to-volume ratio and the reduced mass of the particles can be found in the market. But the quantum and self-organizing properties peculiar to NT are observed to be still far away from being fully exploited at the industrial level. The necessities of advanced old industries to fully benefit the enabling technology characteristics of NTs are also discussed taking the Korean nanodevice industries and nanomedical technologies as an example. This survey leads us to conclude that the commercial sector of Korean NTs shows more innovative characteristics rather than disruptive ones. It is also argued that the market size of energy-related NT and nanomedicine sub-areas has a great potential to grow in near feature. However, insufficient basic researches for the hierarchical assembly o f complicated nanostructures and functionalities, and the need of large investments for their commercializations as well as the public reluctance to accept nano-products will be the main obstacles to the NT commercialization.