• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4215-4220
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• 2011

This study introduces a new concept for a simple, efficient and cheap sensitivity amplification of a Quartz Crystal Microbalance (QCM) based immunosensor system for the detection of tumor necrosis factor-alpha (TNF-${\alpha}$, TNF) by using an in-built magnetic system. The frequency shift due to the applied magnetic field was successfully observed on magnetic particles labeled detection antibodies, anti-human TNF-${\alpha}$, which were bound to the immunologically captured TNF-${\alpha}$ on the gold coated quartz crystals. In the present system, the magnitude of frequency shift depends on both the strength of magnetic field and the amount of target antigen applied. Significant signal amplification was observed when the additional built-in residual stress generated by the modified magnetic particles under the magnetic field applied. Used in conjunction with a sandwich type non-competitive immunoassay format, the lower detection limit was calculated to be 25 $ngmL^{-1}$ and showed good linearity up to TNF-${\alpha}$ concentrations as high as 2.0 ${\mu}gmL^{-1}$. The sensitivity, most importantly, was improved up to 4.3 times compared with the same QCM system which was used only an antigen-antibody binding without additional magnetic amplification.

• Applied Chemistry for Engineering
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• v.34 no.4
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• pp.383-387
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• 2023

The quartz crystal microbalance (QCM), commonly used in high vacuum deposition, becomes difficult to use when a thick film is deposited on the quartz, affecting the crystal's inherent vibration. In this study, a non-destructive optical measurement method was developed to measure the film's deposition rate during the in-situ film deposition process. By measuring the scattered laser intensity caused by the dimer in the parylene gas passing through the gas flow path, it was successfully confirmed that the ratio of the dimer in the parylene gas increases as the pyrolysis temperature decreases. Additionally, it was noted that the film's thickness and haze increase as the pyrolysis temperature decreases by confirming the characteristics of the visible parylene films. Through the research results, we aim to utilize the stable in-situ film deposition rate measurement system to control the precise film deposition rate of parylene films.

• KSBB Journal
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• v.15 no.5
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• pp.497-500
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• 2000

Liposomes and proteoliposomes, artificial membranes, can interact with many solutes, such as drugs, peptides and proteins. The immobilization of (prot대)liposomes as supramolecular aggregates on gold surfaces have potential applications in nano and biosensor technology. We demonstrated a quartz crystal analyzer (QCA) based method to monitor the construction of multi-layers of unilamellar liposomes based on avidin-biotin binding on gold surfaces using a quartz crystal microbalance (QCM). Thus, the QCA provides an on line and efficient method of detecting the construction of protein membranes, which has applications in biosensing systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05b
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• pp.21-23
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• 2002

In this paper, the electrochemical behavior of Viologen self assembly monolayer has been investigated with QCM, which has been known as nano-gram order mass detector. The self assemvly process of Viologen was monitored using resonant frequency $({\Delta}F)$ and resonant resistance(R). QCM measurements indicated a mass adsorption for Viologen assembling on the gold sufrace with a frequency change about 135[Hz] and calculated its surface coverage($\Gamma$) to be $3.5273{\times}10^{-9}[mol/cm^{2}]$. Also reversible redox process was observed and analyzed with ionic interaction at the Viologen/solution interface using ${\Delta}F$.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.2-2
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• 2002

Quartz Crystal Microbalance(QCM)은 표면에 묻은 물질의 미량의 무게변화도 간단히 측정 할 수 있어 반웅기 내에서 일어나는 현상올 in-situ로 즉시 알 수 있는 장점을 가진 장치이 다. 이 장치를 이용하면 초엄계 이산화탄소 내에서 용해도를 알 수 있고, 대상물질이 녹아냐 가는 속도를 측정하면 확산계수를 구할 수 있다. 그리고, 초음파 혼을 반응용기 내에 설치하 고, 초음파 효과를 알아보았다. 먼저 static system에서 초음파 효과를 알아보았다. Cu(acac)2를 대상으로, 밀폐된 용기에서 수행한 실험에서, 액체와 초임계 이산화탄소 내에서 용해속도를 QCM으로 구할 수 있었다. 용해속도로부터 Cu(acac)2의 확산계수를 측정할 수 있었다. 액체 내에선 $10^{-4}{\;}cm2/sec$, 초임계상태에서 $10^{-2}{\;}cm2/sec$의 값을 갖는 것으로 나타 났다. 그리고, 초음파를 사용할 경우 이 확산계수값이 4-5배정도 증가하는 것으로 냐타났다. 이어서 dynamic system에서 반응을 알아보았다. Cyanex를 함유한 C02를 반응용기에 흘리 면서 QCM표면에 묻은 Co이온의 용해속도를 측정하였다. 초음파는 용해도에 아무 역활을 안하는 것으로 나타났다. 주어진 조건에서 13 microgram/gram-cyanex의 용해도를 갖는 것 으로 나타났다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.176-179
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• 2000

In the recognition of the gases using the quartz crystal microbalance (QCM) coated with the film materials, it is important to obtain the recognition ability of gases, and the stability of film coated above the QCM. Especially, the thickness of film coated above the QCM is decreased according with the using circumstance and time of QCM gas sensor. Therefore, the sensing chararcteristics of film is changed with these. In this paper, we coated the lipid PC (Phosphatidyl Choline) materials varing with the blended amount of PVC(Poly Vinyl Chloride) and solution (Tetra Hydrofan:THF) above QCM to obtain the stability of lipid PC film. QCM gas sensors coated with film materials were measured the frequency change in the chamber of stationary gas sensing system injected 1-hexane, ethyl acetate, ethanol and benzene of $20{\mu}{\ell}$, respectively. We obtained the principal component analysis (PCA) from the frequency change due to the absorption of gas. Also, we measured the degradation characteristics of QCM gas sensor to show the properties of stability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.218-222
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• 2002

In the recognition of the gases using the quartz crystal microbalance (QCM) coated with the PEG film materials, it is important to obtain the recognition ability of gases, and the stability of PEG film coated above the QCM. Especially, the thickness of PEG film coated above the QCM is decreased according with the using circumstance and time of QCM gas sensor. Therefore, the sensing characteristics of PEG film is changed with these. In this paper, we coated the PEG materials varing with the blended amount of PVC(Poly Vinyl Chloride) and chloroform above QCM to obtain the sensitive and the stability of PEG film. We measured the degradation characteristics of QCM gas sensor in the ethyle acetate 50[%] concentration to show the properties of stability.

• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.276-280
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• 2001

The self-assembled formation of octadecanethiol (CH3(CH2)17SH) on a gold substrate was studied using a quartz crystal microbalance (QCM) and a scanning tunneling microscope (STM). From the QCM measurements at vario us concentrations of octadecanethiol solutions in hexane and alcohol, the adsorption process of octadecanethiol onto Au was confirmed to consist of two steps as follows: (i) fast but disordered adsorption and (ii) a thermodynamically controlled rearrangement for uniform packing of octadecanethiol. Also, it was revealed that the adsorption rate became faster in ethanol than in hexane since less solubility of octadecanethiol in ethanol could help the formation of the monolayers. At 5 ${\times}$10-7 M solution, the monolayer formation was monitored by STM. The morphology of monolayer region was initially circular (diameter size: 7.26 $\pm$ 2.1 nm) and gradually changed to a stripe type after several minutes. At higher concentration, the self-assembled monolayer was formed immediately after the solution was introduced to a substrate.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.103-110
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• 2015

In this work, the performance of various promoters was investigated used in $CO_2$ separation from the gases emitted from steel-making process using gas hydrate technology. The studied promoters are tetrahydrofuran (THF), propylene oxide and 1,4-dioxane, which are all expected to form a structure II hydrate, and the target gases include $CO_2/N_2$ mixed gases ($CO_2/N_2$ = 20/80 and 40/60) and Blast Furnace Gas (BFG). The phase equilibrium points were measured when each promoter was added with various concentrations. For fast acquisition of abundant data, the "continuous" Quartz crystal microbalance (QCM) method was employed. In addition, the crystal structure of each gas hydrate was analyzed by Powder X-ray diffraction (PXRD).

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.112-118
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• 2012

In this study, physical properties of synthesized DE7-OSA82-AO and DEP52-OSA82-AOQ82 zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity. Phase behavior study was also performed. The dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which was attained using zeta potential measurements and QCM (quartz crystal microbalance) experiments. The isoelectric point of DE7-OSA82-AO surfactant determined by the zeta potential measurement and QCM experiment was about 7.2 and 7.4, respectively. On the other hand, the isoelectric point of DEP52-OSA82-AOQ82 surfactant determined by the zeta potential measurement and QCM experiment was about 10.9 and 11.0, respectively. The frictional property measured using an automated mildness tester showed that DE7-OSA82-AO surfactant can provide a good softening effect at an acidic or neutral condition. On the other hand, DEP52-OSA82-AOQ82 was found to provide a good softening effect to a fabric surface at a pH below its isoelectric point of 11.