• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.470-474
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• 2023

In this study, a diaphragm-type pressure sensor was developed using multi-layer(four-layer) graphene produced at 1 nm thickness by thermally transferring single-layer graphene produced by chemical vapor deposition (CVD) to a 6" silicon wafer. By measuring the gauge factor, we investigated whether it was possible to produce a pressure sensor of consistent quality. As a result of the measurement, the pressure sensor using multilayer graphene showed linearity and had a gauge factor of about 17.5. The gauge factor of the multilayer graphene-based pressure sensor produced through this study is lower than that of doped silicon, but is more sensitive than a general metal sensor, showing that it can be sufficiently used as a commercialized sensor.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.28-35
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• 2000

In this study, we investigated the characteristics of polyurethane synthesis by simultaneously measuring resonant frequency and resonant resistance with a quartz crystal analyzer. The rapid decrease of resonant frequency was appeared because automatic catalytic reaction was caused by the polyurethane formed in initial stage of polyurethane synthesis. In prepolymer(PP) synthesis, the resonant frequency was slowly stabilized after a rapid decrease at a certain point of time. But in segmented polyurethane synthesis in which chain-extender was involved, the resonant frequency increased again after a rapid decrease at a certain point of time. It was considered that this tendency took place because the chain-extender, 1,4-butandiol, caused a soft segment to change to a hard segment. The resonant resistance was used in the analysis of mechanism. From the results, the characteristics of polyurethane synthesis could be analyzed on-line using a quartz crystal analyzer, and the synthesis mechanism could also be interpreted.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.71-75
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• 2023

In this study, inorganic perovskite films with different compositions were grown by thermal chemical vapor deposition depending on the substrate and their optical properties were compared. Inorganic perovskite crystals were grown on SiO₂/Si and c-Al₂O₃ substrates using CsBr and PbBr₂, respectively, under the same growth conditions. Cs₄PbBr₆-CsPbBr₃ crystallites were grown on the SiO₂ with polycrystalline structure, while a CsPbBr₃ (100) dominant thin film was formed on the c-Al₂O₃ substrate with single crystal structure. From the photoluminescence measurement, CsPbBr₃ showed typical green emission centered at 534 nm with a full width at half maximum (FWHM) of about 91 meV. The Cs₄PbBr₆-CsPbBr₃ mixed structure exhibits blue-shifted emission at 523 nm with a narrow FWHM of 63 meV and a fast decay time of 6.88 ns. These results are expected to be useful for application in photoelectric devices such as displays, solar cells, and light sensors based on inorganic metal perovskites.

• Journal of the Korean institute of surface engineering
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• v.57 no.1
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• pp.38-48
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• 2024

We fabricated In₂O₃ zig-zag nanocolumns(ZZNCs) by oblique angle deposition method based on e-beam evaporator for highly sensitive and selective CH₃COCH₃ sensor. Our results indicate that as the ZZNCs layer stacks, the gas response also increases. In comparison to thin films, ZZNCs at 5 layer show a 117-fold enhancement in gas response and a rapid response time (~2 s). When measured with various gases, it showed a high selectivity towards acetone. Under conditions of 80% R.H., exposure to CH₃COCH₃ gas theoretically indicated a detection limit of 1.2 part-per-billion(ppb). These results suggest the potential of In₂O₃ ZZNCs as a breath analyzer for the diagnosis of diabetes.

• International Journal of Precision Engineering and Manufacturing
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• v.7 no.1
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• pp.42-46
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• 2006

This paper presents a method for deposition an individual carbon nanotube (CNT). The alignment of a single CNT is very useful to perform studies related to applications in FET (Field Emitted Transistor), SET (Single Electron Transistor) and to make chemical sensor as well as bio sensors. In this study, we developed the deposition method of a CNT individualized in a solution. Using the electrokinetic method, we found the optimum conditions to assemble the nanotube and discussed about plausible explanation for the assembling mechanism. These results will be available to use for making the CNT sensor device.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.78-81
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• 2015

Pure ZnO and ZnO nanowires doped with 3 wt.% Ga (‘3GZO’) were grown by pulsed laser deposition in a furnace system. The doping of Ga in ZnO nanowires was analyzed by observing the optical and chemical properties of the doped nanowires. The diameter and length of nanowires were under 200 nm and several ${\mu}m$, respectively. Changes of significant resistance were observed and the sensitivities of ZnO and 3GZO nanowires were compared. The sensitivities of ZnO and 3GZO nanowire sensors measured at 300℃ for 1 ppm of ethanol gas were 97% and 48%, respectively.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.36-39
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• 2003

Conducting polymers are finding increasing number of applications in various electronic devices such as chemical sensors, electrochromic display, light emitting diodes, etc. Polyaniline(PANI) ranks among highly prospective conduction polymers. PANI was first synthesis in 1862[1] and has been extensively studied as a conducting polymer since the 1980s[2]. The side range of electrical, electrochemical and optical properties coupled with good environmental stability makes PANI potentially attractive for application as an electronic material. (omitted)

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.243.1-243.1
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• 2010

Devices based on nanomaterials platforms are emerging as a powerful tool for ultrasensitive sensors for the direct detection of biological and chemical species. In this talk, we will report the preparation and the full characterization of electrochemical polymerization of biopolymers platforms and nano-structure formation for electrochemical detection of enzymatic activity and toxic compound in electrolyte for biosensor applications. Formation of an electroactive polymer film of two different compounds has been quantified by observing new redox peak at higher potentials in cyclic voltammogram measurements. RCT value of at various biopolymer concentration based hybrid films has been obtained from electrochemical impedance spectroscopy analysis and possible mechanism for formation of complexes during electrochemical polymerization on conducting substrates has been investigated. Biosensors developed based on these hybrid biopolymers have very high sensitivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.64-64
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• 2009

As the advanced packaging technology developing, Copper electro-plating processing has be wildly utilized in the semiconductor interconnect technique. Chemical solution monitoring methods, including PH and gravity measurement exist in industry, but economical and practical real-time monitoring has not been achieved yet. Red-green-blue (RGB) color sensor can successfully monitor the condition of $CuSO_4$ solution during electric copper plating process. Comparing the intensity variations of the RGB data and optical spectroscopy data, strong correlation between two in-situ sensors have shown.

• Ceramist
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• v.21 no.3
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• pp.283-292
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• 2018

Here, we introduce various type of inorganic nanostructure synthesized with functional nanoparticles and silica. From two decades ago, functional inorganic nanoparticles have been synthesized and highlighted, now we moved to next level of wet-chemical synthesis. By integrating functional nanoparticles with silica, we were able to synthesize multi-functional nanostructure, which expand the applications of nanoparticles to catalyst, drug carrier, sensors. In this context, silica has been spotlighted due to its versatility. Silica has highly biocompatible, relatively transparent and stable under harsh conditions. Thus it can be used as good supporter to synthesize complex multi-functional nanostructure when mixed with other functional nanoparticles. A various shape of complex nanostructures have been synthesized including core-shell type, yolk-shell type and janus type etc. In this paper, we have described the purposes of synthesizing silica noncomplex and various case studies for biomedical applications and self-assembly.