Jin Won Song

Continuous extraction of highly pure metallic single-walled carbon nanotubes in a microfluidic channel

Highly pure metallic single-walled carbon nanotubes were continuously extracted from a mixture of semiconducting and metallic species using a nondestructive, scalable method. Two laminar streams were generated in an H-shaped microfluidic channel with two inlets and two outlets. The flow conditions were carefully controlled to minimize diffusive and convective transport across the boundary between the two flows. Dielectrophoretic force from the embedded electrode at the junction extracted metallic nanotubes from a stream of nanotube suspension toward the other stream of buffer solution without nanotubes. The highly pure metallic and enriched semiconducting nanotubes were obtained simultaneously at each outlet using this novel approach. Excellent selectivity was verified by electrical transport measurement, absorption, and Raman spectroscopic analysis.

Preferential elimination of metallic single-walled carbon nanotubes using microwave irradiation

This study presents a simple, easy and rapid technique for the preferential destruction of metallic single-walled carbon nanotubes (m-SWNTs) using microwave irradiation. The proportion of m-SWNTs in a randomly networked film that were made of pristine SWNTs was gradually reduced with microwave irradiation of 1000 W at 2.45 GHz ranging from 0 to 20 min. Additionally it was observed that the m-SWNTs with a higher chiral angle were destroyed first. The Raman spectra and drain current-gate voltage characteristics curve show that this method facilitated the selective removal of m-SWNTs.

Highly sensitive carbon nanotube-embedding gas sensors operating at atmospheric pressure

Highly sensitive palladium (Pd) decorated carbon nanotube (CNT) embedding gas sensors working at atmospheric pressure were fabricated. Two types of gas sensors of bare CNTs and Pd nanoparticle decorated CNTs were synthesized by dielectrophoresis. The CNT-containing solution was dropped onto the patterned-platinum electrodes with ac bias. The CNT-embedding sensors sensitively detected 100 ppb level of NO(2) in an atmospheric pressure condition. The Pd decoration on CNTs forming the depletion region was found to be an effective way to enhance the sensor response by the control of carrier mobility and density. Raman spectroscopy revealed a low defect ratio of D/G(-) by heat treatment at 450 degrees C. Moreover, it was investigated that there exists an optimum temperature to enhance the sensor response.

Fabrication of carbon nanotube sensor device by inkjet printing

To overcome the limitation of conventional carbon nanotube fabrication techniques, inkjet printing was directly utilized on a whole wafer. In this work, inkjet printing method was used as a strong technique for the massive production of gas sensor applications. As a single wafer processing, it provided the great potential to fabricate uniform and reproducible single walled carbon nanotube (SWCNT) films on desired positions in terms of electrical characteristics and gas reaction performances. In order to secure good electrical contact between SWCNTs and the metal electrode, SWCNTs were firstly printed on a wafer with insulation layer, and then the metal electrodes were patterned by using lift-off process. The fabricated gaps of the electrodes were 2, 4, and 8 m, respectively. SWCNT films contacted tightly beneath the electrode show low and uniform electrical resistance values of 96-281 and reliable gas detection performances as well. In this work, As-deposited devices exhibit about 3% sensitivities to 100ppb - NO2 in 10 minutes and increased up to 9% by the annealing treatments at 400degC.

Resonance charaterizaion of multi-wall cabon nanotubes

We report the suspended assembly for the fabrication of resonator using multi-wall carbon nanotubes (MWNT). To vibrate a MWNT on plane surface, it should need suspension of a MWNT across trench electrodes. So we propose fabrication method of a MWNT resonator using dielectrophoresis (DEP). By drying the solution during DEP assembly, the capillary force pulls the MWNT toward the bottom substrate, and the MWNT then remains as a deformed structure adhering on the bottom substrate after the solution has dried out. Show successful results which are some SEM images of suspended MWNT. And so, resonances can be detected.

Assembly and Characterization of Nanodevice using Carbon Nanotubes and Nanowires

We report the assembly and characterization of three types of Ag, SnO2, and Ga2O3 nanowires (NWs) and two types of carbon nanotubes (NTs) using dielectrophoresis. The NWs and NTs were individually assembled using an experimental approach based on the dielectrophoretic force equation. After depositing a Pt top electrode using a focused ion beam, we investigated the I-V curves of NW and NT devices.

Fabrication and charaterizaion of resonator using multi-wall cabon nanotubes

We report the suspended assembly for the fabrication of resonator using multi-wall carbon nanotubes (MWNT). To vibrate a MWNT on plane surface, it should need suspension of a MWNT across trench electrodes. So we propose fabrication method of a MWNT resonator using dielectrophoresis (DEP). By drying the solution during DEP assembly, the capillary force pulls the MWNT toward the bottom substrate, and the MWNT then remains as a deformed structure adhering on the bottom substrate after the solution has dried out. In addition, the theoretical and experimental considerations of resonance of fabricated device were discussed.

Assembly technique and charaterizaion for the nanodevice using dielectrophoresis

We report the assembly for the fabrication of nanodevices using nanowires (NWs). The nanowires were individually assembled using an experimental approach based on the dielectrophoretic force equation. After depositing a Pt top electrode using a focused ion beam, we investigated the I-V curves of nanodevices. We used control the thickness of the bottom electrode for the suspension from the bottom electrode. We found that their conductivities in nanodevices were remarkably increased along with the increase of the suspension height.