• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.111-116
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• 2006

In this paper, the image sensor using the a-Si:H TFT is proposed. The optimum amorphous silicon thin film is deposited using plasma enhanced chemical vapor deposition (PECVD). TFT and photodiode both with the thin film are fabricated and form image sensor. The photodiode shows that Idark is $10^{-12}A$, Iphoto is $10^{-9}A$ and Iphoto/Idark is $10^3$, respectively. In the case of a-Si:H TFT, it indicates that Ion/Ioff is $10^6$, the drain current is a few ${\mu}A$ and Vth is $2\~4$ volts. For the analysis on the fabricated image sensor, the reverse bias of -5 voltage in ITO of photodiode and $70{\mu}sec$ pulse in the gate of TFT are applied. The image sensor with good property was conformed through the measured photo/dark current.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.35-40
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• 1996

The polymeric membrane pH sensor based on HDBA(hexyldibenzylamine) or HDPA(hexyldiphenylamine) as hydrogen ion carrier was prepared and electrochemical characterization for the variation of a temperature and membrane thickness were studied on. The sensor based on HDPA was not responded selectively to hydrogen ion. The sensor based on HDBA was responded linearly to hydrogen ion in the range of pH 2 - pH 10, it showed the fast response time of 30 - 50sec. and Nernstian slope of 53.6mV/pH. The interfering effect on alkali and alkaline earth metal ions of pH sensor were lower than glass pH sensor. There was shown a good reproducibility and stability with the precision of 2 - 4mV (${\pm}0.1mV$).

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1474-1476
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• 2004

A sodium ion- selective electrode based on dibenzopyridino-18-crown-6 as membrane carrier was successfully prepared. The electrode exhibits a Nernstian response for $Na^+$ ions within the concentration range of $1.0\;{\times}\;10^{-4}-1.0\;{\times}\;10^{-1}$ M. The response time of the sensor is 20 s. The sodium ion-selective electrode exhibited comparatively good selectivities with respect to alkali, alkaline earth and some transition metal ions.

• Journal of Powder Materials
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• v.30 no.4
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• pp.310-317
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• 2023

Small-film-type ion sensors are garnering considerable interest in the fields of wearable healthcare and home-based monitoring systems. The performance of these sensors primarily relies on electrode capacitance, often employing nanocomposite materials composed of nano- and sub-micrometer particles. Traditional techniques for enhancing capacitance involve the creation of nanoparticles on film electrodes, which require cost-intensive and complex chemical synthesis processes, followed by additional coating optimization. In this study, we introduce a simple one-step electrochemical method for fabricating gold nanoparticles on a carbon nanotube (Au NP-CNT) electrode surface through cyclic voltammetry deposition. Furthermore, we assess the improvement in capacitance by distinguishing between the electrical double-layer capacitance and diffusion-controlled capacitance, thereby clarifying the principles underpinning the material design. The Au NP-CNT electrode maintains its stability and sensitivity for up to 50 d, signifying its potential for advanced ion sensing. Additionally, integration with a mobile wireless data system highlights the versatility of the sensor for health applications.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2577-2582
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• 2013

A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM)2) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the $Ni(DBM)_2$ ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by $Ni(DBM)_2$ across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over $Br^-$, $NO_2{^-}$, $NO_3{^-}$, $CO{_3}^{2^-}$, $CH_3COO^-$ and $SO{_4}^{2^-}$ ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.

• Journal of the Korean Electrochemical Society
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• v.5 no.4
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• pp.212-215
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• 2002

A superoxide dismutase (SOD)-based superoxide ion $(O_2^-)$ sensor was fabricated by immobilizing SOD on a self-assembled monolayer (SAM) of 3-mercaptopropionic acid (MPA) which was prepared on a gold electrode. The SAM of MPA was found to function as an effective promoter for the electrode reaction of SOD. The amperometric response to $(O_2^-)$ was monitored at 300mV and -100mV vs. Ag/ Agel in 5mM phosphate buffer solution containing $KO_2$. The sensor was proved to have a high sensitivity, selectivity and short response time (<5 s) and negligible interference.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.77-88
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• 2013

The computational study on the fluoride ion binding with bis(bora)calix[4]arene has been performed using density functional theory and ONIOM model. The computed structure and fluorescent behavior of bis(bora)calix[4]arene was corresponded to experiment value. The binding energy for fluoride anion is computed to be 28.05kJ/mol in the chloroform solution. We also predicted that this sensing mechanism is only valid for fluoride ion in halogens. By analyzing molecular orbitals, binding with fluoride ion reduces energy differences between HOMO and LUMO, which leads to fluorescent sensing.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.463-471
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• 2023

Nitrogen-rich carbon dots (NDots) were synthesized by using uric acid as carbon and nitrogen sources. The as-synthesized NDots showed strong dual emissions at 420 nm and 510 nm with excitation at 350 nm and 460 nm, respectively. The physicochemical analyses such as X-ray photoelectron spectroscopy, Transmission electron microscopy and Fourier transform infrared spectroscopy were used to analyze the chemical, physical and morphological structures of NDots. The as-synthesized NDots exhibited wide linear range (0-100 µM) and very low detection limit (124 nM) in Ag⁺ ion sensing. In addition, Ag⁺ saturated NDots could be used as an EDTA sensor by the EDTA induced PL recovery.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.846-850
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• 2003

Thin film $SnO_2$ Gas Sensor was fabricated by using ion beam sputtering and ultra thin film Pt catalyst of $45{\AA}$ was deposited on $SnO_2$ thin film. The effects of annealing temperature on the structural properies of $SnO_2$ were investigated using the X-ray diffraction. Using SEM, microstructures of thin film were investigated. The good gas sensitivity is shown when annealing condition is $650^{\circ}C$, 5hr and ultra thin film Pt catalyst thickness is $45{\AA}$.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3088-3092
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• 2013

A novel PVC membrane sensor for perindopril based on perindopril-phosphotungstate ion pair complex was prepared. The influence of membrane composition (i.e. percent of PVC, plasticizer, ion-pair complex, and kind of plasticizer), inner solution, pH of test solution and foreign cations on the electrode performance was investigated. The optimized membrane demonstrates Nernstian response ($30.9{\pm}1.0$ mV per decade) for perindopril cations over a wide linear range from $9.0{\times}10^{-7}$ to $1{\times}10^{-2}$ M at $25^{\circ}C$. The potentiometric response is independent of the pH in the range of 4.0-9.5. The proposed sensor has the advantages of easy preparation, fast response time. The selectivity coefficients indicate excellent selectivity for perindopril over many common cations (e.g., $Na^+$, $K^+$, $Mg^{2+}$, $Cu^{2+}$, $Ni^{2+}$, rhamnose, maltose, glycine and benzamide. The practical applications of this electrode was demonstrated by measuring the concentrations of perindopril in pure solutions and pharmaceutical preparations with satisfactory results.