• Title, Summary, Keyword: Microbalance

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The Impedance Properties of Quartz Crystal Microbalance Coated with LB films (LB막을 누적한 수정진동자의 임피던스 특성)

  • 진철남;김경환;유승엽;박재철;권영수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.171-174
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    • 1998
  • Quartz crystal in contact with viscoelastic medium is described directly in terms of the electrical equivalent circuit of the system. Stearic acid is used as viscoelastic medium and deposited on the surface of quartz crystal using the Langmuir-Blodgett(LB) method. Impedance properties of quartz crystal coated with LB films which were investigated and the possibility of applying the technique to chemical sensing introduced.

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Characterization of Surface Films Formed Prior to Bulk Reduction of Lithium in Rigorously Dried Propylene Carbonate Solutions

  • Chang, Seok Gyun;Lee, Hyo Jung;Gang, Heon;Park, Su Mun
    • Bulletin of the Korean Chemical Society
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    • v.22 no.5
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    • pp.481-487
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    • 2001
  • Surface films formed prior to bulk reduction of lithium have been studied at gold, platinum, and copper electrodes in rigorously dried propylene carbonate solutions using electrochemical quartz crystal microbalance (EQCM) and secondary ion mass spectrometry experiments. The results indicate that the passive film formation takes place at a potential as positive as about 2.0 V vs. Li/Li+ , and the passive film thus formed in this potential region is thicker than a monolayer. Quantitative analysis of the EQCM results indicates that electrogenerated lithium reacts with solvent molecules to produce a passive film consisting of lithium carbonate and other compounds of larger molecular weights. The presence of lithium carbonate is verified by SIMS, whereas the lithium compounds of low molecular weights, including lithium hydroxide and oxide, are not detected. Further lithium reduction takes place underneath the passive film at potentials lower than 1.2 V with a voltammetric current peak at about 0.6 V.

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Hydrogen Absorption Characteristics of Al/Pd Film (Al/Pd 박막의 수소 흡수 특성)

  • Cho, Young-Sin
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.2
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    • pp.234-240
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    • 2006
  • Al film(135.5 nm thick) with Pd film(39.6 nm thick) on the top of it was made by thermal evaporation method. Hydrogen absorption of Al/Pd film was measured by quartz crystal microbalance(QCM) method at room temperature. The sample was activated by hydrogen absorption and desorption cycling at room temperature. Hydrogen was introduced into the film by increasing hydrogen gas pressure step by step up to 640 torr at room temperature. Hydrogen concentration reached up to 25% at $5{\sim}10$ torr. But at high pressure the concentration decreased. This strange tendency was not understood yet. Further study is needed to find out the mechanism of hydrogen absorption in Al in Al/Pd film.

Optimization of Quartz Crystal Microbalance-Precipitation Sensor Measuring Acetylcholinesterase Activity

  • Kim, Nam-Soo;Park, In-Seon;Kim, Dong-Kyung
    • Journal of Microbiology and Biotechnology
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    • v.16 no.10
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    • pp.1523-1528
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    • 2006
  • The optimization of a batch-type quartz crystal microbalance (QCM)-precipitation sensor measuring acetylcholinesterase (AChE) activity was conducted. To covalently bind AChE onto the gold electrode of a QCM surface, glutaraldehyde cross-linking to a cystamine self-assembled monolayer was tried at different cystamine concentrations. At the optimum conditions of the QCM-precipitation sensor, 0.1 M potassium phosphate buffer (pH 8.0), containing 0.01% Tween 80, was used as the reaction buffer, with the enzyme amount of 5 units for immobilization and the substrate concentration of 50 mg/ml. The current biosensor might find a future applicability to the sum parameter detection on organophosphorus and carbamate pesticides.

Performance Evaluation of Explosive Specific Bio-receptor Using QCM Sensing Platform for Resonance Frequency Shift Detection (공진점변화검출용 QCM 센싱플랫폼을 이용한 폭발물 특이적 바이오수용체 성능평가)

  • Lim, Si-Hyung;Jeong, Hyun-Jin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.3
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    • pp.280-284
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    • 2011
  • The mass change during the molecular interaction between explosive specific bio-receptors and target molecules has been measured using quartz crystal microbalance(QCM), which has a mass change detection limit up to ~ng/$cm^2$. The environmental effect on the molecular interaction has been evaluated. In the liquid phase molecular interaction experiments, the high selectivity of the bio-receptor to DNT compared with toluene has been shown and the sensitivity for various concentrations of DNT has been demonstrated.

On-Line Measurement of Solid Particles in Air Using a Quartz Crystal Microbalance (수정진동자 미량저울을 이용한 공기 중 먼지의 온라인 측정)

  • Choi, Kwang-Jae;Kim, Young-Han;Chang, Sang-Mok
    • Journal of Sensor Science and Technology
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    • v.8 no.4
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    • pp.314-319
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    • 1999
  • The measurement of solid particles suspended in air is conducted with a quartz crystal microbalance. The measurement system is connected to a personal computer and multiple sensors are utilized to make simultaneous measurement possible. In this paper, the detail of experimental setup is extensively explained for the possible future application of the system in other areas. It is found that the measurement system is suitable for an on-line continuous determination of the concentration of solid particles in air.

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Corrosion of Silver by Outgassing from Rubber

  • Sakai, Jun'ichi;Omoda, Masataka;Ishikawa, Yuichi
    • Corrosion Science and Technology
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    • v.7 no.2
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    • pp.130-133
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    • 2008
  • Corrosion of silver by outgassed sulfur species from rubber has been investigated by means of quartz crystal microbalance technique (QCM) and cathodic reduction technique. Silver specimens were placed together with a rubber of predefined quantity in an enclosed environment. Corrosion progressed linearly with time and silver sulfide was found as the corrosion product during all the tests. No significant dependence on RH was observed, while the corrosion rate increased as temperature rose. Furthermore the corrosion rate increased logarithmically with the quantity of the rubber placed in the exposure environment. It may be suggested that the corrosion rate of silver is determined by the amount of outgassed sulfur species which is a function of temperature and the quantity of rubber contained in the exposure environment.

QCM Study of β-Casein Adsorption on the Hydrophobic Surface: Effect of Ionic Strength and Cations

  • Lee, Myung-Hee;Park, Su-Kyung;Chung, Chin-Kap;Kim, Hack-Jin
    • Bulletin of the Korean Chemical Society
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    • v.25 no.7
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    • pp.1031-1035
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    • 2004
  • The adsorption kinetics of ${\beta}$-casein on a hydrophobic surface has been studied by means of the quartz crystal microbalance (QCM). The self assembled monolayer of 1-octadecanethiol on a gold coated quartz crystal was used as a hydrophobic surface for adsorption. The adsorption kinetics was monitored in different solution conditions. Formation of monolayer is observed in most cases. At high concentration of protein, micelle formation which is interrupted by high ionic strength of solution is observed. Casein binding cations such as $Ca^{2+},\;Ba^{2+}\;and\;Al^{3+}$ increase the hydrophobicity of the protein and the multiple layer adsorption occurs. The strong and weak points of the QCM method in the study of protein adsorption are discussed.

QCM biosensor for the determination of haptoglobin (헵토글로빈 측정을 위한 수정미소저울 바이오센서 개발)

  • Kim, Sung-Il;Lee, Hyeon-Jeong;Park, Soon-Hyuk;Bhang, Hyun-Soo;Lee, Jin-Ah;Choi, Suk-Jung
    • Journal of Sensor Science and Technology
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    • v.16 no.2
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    • pp.132-141
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    • 2007
  • The purpose this research is to develop QCM (quartz crystal microbalance) biosensor for the determination of haptoglobin. Haptoglobin is an acute-phase protein with a hemoglobin-binding activity and has a potential to be used as a biomarker for infection or cancer. Haptoglobin level in milk has been used for the diagnosis of cow mastitis. In this study, anti-bovine haptoglobin antibody or bovine hemoglobin was chemically immobilized on the surface of the QCM, and the resulting sensor chips were tested for their response to samples containing haptoglobin at different concentrations. Concentration dependent frequency change was observed with both of the sensor chips. Especially, the sensor chip containing anti-bovine haptoglobin antibody showed sufficient sensitivity in the concentrations typically observed in the cows with mastitis.

Study on Morphology Investigation and Electron-Transfer Property of Self-Assembled Viologen Monolayers (자기조립된 Viologen 단분자막의 모폴로지 관찰과 전하이동 특성 연구)

  • Lee, Dong-Yun;Park, Sang-Hyun;Kwon, Young-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.395-396
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    • 2005
  • We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. We determined the time dependence to resonant frequency shift during self-assembly process and observed the morphology of self-assembled mono layers by STM and investigated the electrochemical behavior of SAMs by cyclic voltammetry. Electrochemical deposition of viologen was investigated using electrochemical quartz crystal microbalance(EQCM). The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redox reactions.

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