• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.821-827
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• 2007

The nitrogen oxides, NO and $NO_2$, abbreviated usually as NOx, emitted from combustion facilities such as power plants and automobiles are the typical air-pollutants causing acid rain and photochemical smog. In order to solve the NOx-related pollution problems effectively, we need efficient techniques to monitor NOx in the combustion exhausts and in environments. Development of solid-state electrochemical devices for detecting NOx is demonstrated based on various combination of solid electrolytes and auxiliary sensing materials. The object of this research is to develop various sensor performance for solid state amperometric sensor, and to test gas sensor performance manufactured. So we try to present a guidance for developing amperometric gas sensor. We concentrated on development of manufacturing process and performance test. Amperometric Nitrogen dioxide sensor was fabricated using NASICON and an $NaNO_2$ layer deposited on the counter electrode. The current response was almost linear with Nitrogen dioxide concentration in the range 1-350 ppb at $150^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.912-917
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• 2007

Many electrochemical power devices such as solid state batteries and solid oxide fuel cell have been studied and developed for solving energy and environmental problems. An amperometric gas sensor usually generates sensing signal of electric current along the proportion of the concentration of target gas under the condition of limiting current. For narrow variations of gas concentration, the amperometric gas sensor can show higher precision than a potentiometric gas sensor does. In additional, cross sensitivities to interfering gases can possibly be mitigated by choosing applied voltage and electrode materials properly. In order to improve the sensitivity to $NO_2$, the device was attached with Au reference electrode to form the amperometric gas sensor device with three electrodes. With the fixed bias voltage being applied between the sensing and counter electrodes, the current between the sensing and reference electrodes was measured as a sensing signal. The response to $NO_2$ gas was obviously enhanced and suppressed with a positive bias, respectively, while the reverse current occurred with a negative bias. The way to enhance the sensitivity of $NO_2$ gas sensor was thus realized. It was shown that the response to $NO_2$ gas could be enhanced sensitivity by changing the bias voltage.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.95-101
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• 2009

A simple and new CMOS potentiostat circuit for amperometric sensor is described. To maintain a constant potential between the reference and working electrodes, only one differential difference amplifier (DDA) is needed in proposed design, while conventional potentiosatat requires at least 2 operational amplifiers and 2 resistors, or more than 3 operational amplifiers and 4 resistors for low voltage CMOS integrated potentiostat. The DDA with rail-to-rail design not only enables the full range operation to supply voltage but also provides simple potentiostat system with small hardwares and low power consumption.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1073-1075
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• 2001

The nitrogen oxides, NO and NO2, abbreviated usually as NOx, emitted from combustion facilities such as power plants and automobiles are the typical air-pollutants causing acid rain and photochemical smog. In order to solve the NOx-related pollution problems effectively, we need efficient techniques to monitor NOx in the combustion exhausts and in environments. Development of solid-state electrochemical devices for detecting NOx is demonstrated based on various combination of solid electrolytes and auxiliary sensing materials. The object of this research is to develop various sensor performance for solid state amperometric sensor, and to test gas sensor performance manufactured. So we try to present a guidance for developing amperometric gas sensor. We concentrated on development of manufacturing process and performance test.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.222-225
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• 2002

The nitrogen oxides, NO and NO2, abbreviated usually as NOx, emitted from combustion facilities such as power plants and automobiles are the typical air-pollutants causing acid rain and photochemical smog. In order to solve the NOx-related pollution problems effectively, we need efficient techniques to monitor NOx in the combustion exhausts and in environments. Development of solid-state electrochemical devices for detecting NOx is demonstrated based on various combination of solid electrolytes and auxiliary sensing materials. The object of this research is to develop various sensor performance for solid state amperometric sensor, and to test gas sensor performance manufactured. So we try to present a guidance for developing amperometric gas sensor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.924-926
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• 2000

The nitrogen oxides, NO and NO2, abbreviated usually as NOx, emitted from combustion facilities such as power plants and automobiles are the topical air-pollutants causing acid rain and photochemical smog. In order to solve the NOx-related pollution problems effectively, we need efficient techniques to monitor NOx in the combustion exhausts and in environments. Development of solid-state electrochemical devices for detecting NOx is demonstrated based on various combination of solid electrolytes and auxiliary sensing materials. The object of this research is to develop various sensor performance for solid state amperometric sensor, and to test gas sensor performance manufactured. So we try to present a guidance for developing amperometric gas sensor. We concentrated on development of manufacturing process and performance test.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.44-48
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• 2004

The two-component type enzyme amplified amperometric DNA assay is described to use an ambient $O_2$ of the substrate of the DNA labeling enzyme. Although the assay detects DNA only at > 0.5M concentration, a concentration $\~10^6$ fold higher than the sandwich-type enzyme amplified amperometric DNA assay, it can be run with an always available substrate. The assay utilizes screen-printed carbon electrodes (SPEs) which were pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a 37-base long single-stranded DNA sequence. The DNA in the electron conducting film hybridizes and captures, when present, the 37-base long detection-DNA, which is labeled with bilirubin oxidase (BOD), an enzyme catalyzing the four-electron reduction of $O_2$ to water. Because the redox hydrogel electrically connects the BOD reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electrocatalytic for the reduction of $O_2$ to water when the electrode is poised at 200 mV vs. Ag/hgCl. The advantage or the assay over the earlier reported sandwich type enzyme amplified amperometric DNA assay, in which the amplifying enzyme was horseradish peroxidase, is that it utilizes ambient $O_2$ instead of the less stable and naturally unavailable $H_2O_2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.354.1-354.1
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• 2016

Nanoporous gold (NPG) is a very promising material in various fields such as sensor, actuator, and catalysis because of its high surface to volume ratio and conducting nature. In this study, we fabricated a NPG based amperometric sensor on a glass substrate by means of co-sputtering of Au and Si. During the sputtering process, we found the optimum conditions for heat treatment to reduce the residual stress and to improve adhesion between NPG films and the glass substrate. Subsequently, Si was selectively etched from Au-Si alloy by KOH solution, which forms nanoporous structures. Scanning electron microscopy (SEM) and auger electron spectroscopy (AES) were used to estimate the structure of NPG films and their composition. By employing appropriate heat treatments, we could make very stable NPG films. We tested the performance of NPG sensor with aniline molecules, which shows high sensitivity for sensing low concentration of aniline.

• Analytical Science and Technology
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• v.7 no.2
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• pp.149-153
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• 1994

An amperometric sensor for L-ascorbic acid(AA) in methanol media has been made by immobilizing squash-tissues on a graphite rod disk. A detection limit of the electrode was $2{\times}10^{-6}M$ L-ascorbic acid. In comparison with an isolated enzyme based ascorbate oxidase(AO) electrode, the plant-tissue electrode offered high biocatalytic stability and activity and extremely low cost. The electrode has a useful lifetime of 1 week.