• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.210-210
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• 2011

Ultrasmall electodes are of great importance for basic electrochemical study and applications. We fabricated single crystal (111) Au nanowire (NW) by growth mechanism on substrate without any catalyst. Consequently, these high aspect NW combined with tungsten microwire and the electrodes having NW tip on their end were obtained. These single crystal Au (111) NWs were characterized by electron microscope and electrochemical analysis. We show that precise electrochemical measurement could be possible on these NW electrode by obtaining underpotential deposition (UPD) and ferricyanide CV profiles on the electrode. The immersed depth of electrode into solution was controlled in micrometer scale by piezo-driven manipulator.

• Analytical Science and Technology
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• v.8 no.4
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• pp.637-642
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• 1995

The presence of a porous Si layer(PSL) formed on the surface of crystalline silicon by electrochemical etclling in HF solution is found to enhance the stability of n-Si photoanodes, but porous n-Si thus formed is still liable to corrode upon exposure to excitation light. To improve the stability of the porous n-Si electrodes and to reduce the photo-induced corrosion, we have examined the PEC behavior of porous n-Si modified with polyaniline(PANI) and 3 nm thick layer of Au. Comparisons were made between Au/PSL and PANl/Au/PSL photoelectrodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.65-70
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• 2006

In this study, a DNA chip with a microelectrode array was fabricated using microfabrication technology. Several probe DNAs consisting of mercaptohexyl moiety at their 5 end were immobilized on the gold electrodes by DNA arrayer. Then target DNAs were hybridized and reacted with Hoechst 33258, which is a DNA minor groove binder and electrochemically active dye. Linear sweep voltammetry or cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. It was derived from Hoechst 33258 concentrated at the electrode surface through association with formed hybrid. It suggested that this DNA chip could recognize the sequence specific genes.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1175-1180
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• 2013

A microfabricated electrochemical cell comprising PDMS-based microchannel and in-channel gold microelectrodes was fabricated as a sensitive and a miniature alternative to the conventional electroanalytical systems. A reproducible fabrication procedure enabled patterning of multiple microelectrodes integrated within a PDMS-based fluidic network. The active area of each electrode was $200{\mu}m{\times}200{\mu}m$ with a gap of $200{\mu}m$ between the electrodes which resulted in a higher signal to noise ratio. Also, the PDMS layer served the purpose of shielding the electrical interferences to the measurements. Analytes such as potassium ferrocyanide; amino acid: cysteine and nucleoside: guanosine were characterized using the fabricated cell. The microchip was comparable to bulk electrochemical systems and its applicability was also demonstrated with flow injection based rapid amperometric detection of DNA samples. The device so developed shall find use as a disposable electrochemical cell for rapid and sensitive analysis of electroactive species in various industrial and research applications.

• Journal of the Korean Electrochemical Society
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• v.9 no.3
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• pp.113-117
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• 2006

The electrochemical properties of the redox mediator, 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) ($ABTS^{2-}$) were studied using cyclic voltammetry. The measured potentials (${E^o}'$ vs SCE) of the two redox couples of ABTS are 0.45 V for $ABTS^{2-}/ABTS^{\cdot-}$ and 0.87 V for $ABTS^{\cdot-}/ABTS^0$. The rate constant for heterogeneous electron transfer and the diffusion coefficients for $ABTS^{2-}$ are $5x10^{-3}cm\;s^{-1}$ and $3.1x10^{-6}cm^2\;s^{-1}$, respectively. Our interest in $ABTS^{2-}$ stems from the fact that this molecule functions as a substrate to the copper oxidase, laccase, by providing the reducing equivalents necessary for the biocatalyzed reduction of dioxygen to water. Consequently, when laccase is tethered to an electrode surface or dissolved in solution, $ABTS^{2-}$ can be used to quantify enzyme activity electrochemically.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.729-737
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• 2004

In this paper, a DNA chip with a microelectrode array was fabricated using microfabrication technology. Several probe DNAs consisting of mercaptohexyl moiety at their 5 end were immobilized on the gold electrodes by DNA arrayer. Then target DNAs were hybridized and reacted with Hoechst 33258, which is a DNA minor groove binder and electrochemically active dye. Linear sweep voltammetry or cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. It was derived from Hoechst 33258 concentrated at the electrode surface through association with formed hybrid. It suggested that this DNA chip could recognize the sequence specific genes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.598-601
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• 1999

There is currently considerable interest in the applications of conjugated polymers, oligomers and small molecules for thin-film electronic devices. Organic materials have potential advantages to be utilized as semiconductors in field effect transistor and light emitting didoes. In this study, Pentacene thin film transistors(TFTs) were fabricated on glass substrate. Aluminum and Gold wei\ulcorner used fur the gate and source/drain electrodes. Silicon dioxde was deposited as a gate insulator by PECVD and patterned by R.I.E. The semiconductor layer of pentacene was thermally evaporated in vaccum at a pressure of about 10$^{-8}$ Torr and a deposition rate 0.3$\AA$/sec. The fabricated devices exhibited the field-effect mobility as large as 0.07cm$^2$/Vs and on/off current ratio larger than 10$^{7}$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.372-373
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• 2006

In this paper, a DNA chip with a microelectrode array was fabricated using microfabrication technology. Several probe DNAs consisting of mercaptohexyl moiety at their 5 end were immobilized on the gold electrodes by DNA arrayer. Then target DNAs were hybridized and reacted with Hoechst 33258, which is a DNA minor groove binder and electrochemically active dye. Linear sweep voltammetry or cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. It was derived from Hoechst 33258 concentrated at the electrode surface through association with formed hybrid. It suggested that this DNA chip could recognize the sequence specific genes.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.268.1-268.1
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• 2013

Immobilization of conducting nanoparticles on a nanogap comprising two electrodes spaced at a distance comparable to the particle size can be used as a simple and sensitive method of detecting the particles. In this work, we have examined the performance of the nanogap devices in the measurement of metallic nanoparticles, particularly gold nanoparticles (Au NPs). Detection of pM-level Au NPs in an aqueous suspension was quite straightforward irrespective of the existence of non-conducting materials. Speed of detection or the time necessary for the completion of the measurement, however, was strongly dependent upon the immobilization process. Active trapping process was found to be much more efficient and also effective in the detection of nanoparticles than its passive counterpart.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1038-1042
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• 1994

The amperometric responses of thiourea were studied in 0.1 M NaOH by flow injection analysis. D. C. amperometric and pulsed amperometric detection methods were applied for the determination of thiourea at novel metal electrodes such as Pt and Au. Triple-step potential waveforms were adopted in the pulsed amperometric detection. With an optimized pulsed waveform, the current for the oxidation of thiourea was examined with the variation of flow rate of carrier solution and with the change in the amount of sample injected. Gold working electrode turned out to be better in sensitivity and signal to noise ratio than Pt electrode in the pulsed amperometric detection of thiourea. Detection limit is estimated to be 5.33 ${\times}$ 10$^{-5}$ M with this detection method.