• Title, Summary, Keyword: Microbalance

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A Study on the PZT Application for Spacecraft Components under Space Environment (우주환경하의 위성부품용 압전진동자 활용에 관한 연구)

  • Lee, Sang-Hoon;Moon, Guee-Won;Yoo, Seong-Yeon
    • Journal of the Korean Vacuum Society
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    • v.21 no.6
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    • pp.287-294
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    • 2012
  • In the high vacuum condition of the space, outgassing from any assembly of satellite can contaminate satellites, especially second surface mirror and optical lens, it cause satellite to fail in own missions. Therefore, all unit shall be check for compatibility with vacuum using CVCM (Collected Volatile Condensable Material) and TML (Total Mass Loss) in advance. CVCM and TML of the PZT-5 piezoelectric ceramic vibrator has less than 0.1% and 1.0% respectively. Also, it has less than 500 $ng/cm^2/hr$ of Thermoelectric Quartz Crystal Microbalance for vacuum bake-out test using high temperature(more than $80^{\circ}C$) and high vacuum (less than $5.0{\times}10^{-3}$ Pa). Thus, piezoelectric ceramic vibrator may be employed in the vacuum environments. Finally, it can be confirmed that the characteristics change of the piezoelectric ceramic vibrator is less than 1% under vacuum environments.

Detection of C-Reactive Protein Using Direct-binding Quartz Crystal Microbalance Immunosensor (직접결합방식 수정진동자 면역센서에 의한 C-Reactive Protein 검출)

  • Kim, N.;Kim, D.K.;Cho, V.J.
    • KSBB Journal
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    • v.22 no.6
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    • pp.443-446
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    • 2007
  • A prognostic indicator of coronary heart disease, C-reactive protein, was tried to be determined by a batch-type quartz crystal microbalance immunosensor. The sensor was operated by direct-binding mode and the optimum concentration for the corresponding antibody for immobilization was $50{\mu}g/ml$. The reaction buffer for the system was 0.1 M sodium phosphate (pH 7.0) and system operation was performed in the order of baseline stabilization, analyte addition and measurement, and regeneration of the sensor chip with 10 mM NaOH. When plotted in double-logarithmic scale, the sensor showed a linear detection range of 0.27-106.00 nM for rat C-reactive protein with the limit of detection of 0.53 nM. It also showed a good reusability.

A QCM-based Sensor System for Detecting NO2 and SO2 (QCM기반 NO2와 SO2 감지용 센서시스템)

  • Hwang, Min-Jin;Shim, Wang Geun;Moon, Hee
    • Korean Chemical Engineering Research
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    • v.51 no.2
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    • pp.285-291
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    • 2013
  • The effects of sensing materials, coating methods, diluent gases, and temperature have been studied in detail to make a quartz crystal microbalance based adsorption sensor system for detecting gases. In particular, sensor elements for detecting $NO_2$ and $SO_2$, that are known as major air pollutants, have been prepared by coating two different polymers, polypyrrole and poly(3,4-ethylenedioxythiophene). The sensor elements prepared in this work have high sensitivity and selectivity for $NO_2$ and $SO_2$ at ppm level concentrations. It was proven that the sensing characteristics and response rate of the sensing elements are highly dependent on the coating method and the loading mass of sensing materials.

Measurement of Isoelectric Point of Amine Oxide Zwitterionic Surfactant by QCM (Quartz Crystal Microbalance) (QCM (Quartz Crystal Microbalance)을 활용한 Amine Oxide 양쪽성 계면활성제의 등전점 측정에 관한 연구)

  • Kim, JiSung;Park, JunSeok;Lim, JongChoo
    • Applied Chemistry for Engineering
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    • v.20 no.1
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    • pp.9-14
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    • 2009
  • A zwitterionic surfactant shows not only detergency but also softening effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH of the aqueous solution. In this study, the dual function characteristics of an amine oxide zwitterionic surfactant were investigated by measuring the zeta potential and the isoelectric point using quartz crystal microbalance (QCM). In addition, the physical properties of an amine oxide surfactant such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was also performed. The isoelectric point of an amine oxide surfactant determined by zeta potential measurement was near 7.35 and that obtained by QCM experiment was about 7.4, where both results were found to be close to the value reported in the literature.

Measurement of Isoelectric Point of Betaine Zwitterionic Surfactant by QCM(Quartz Crystal Microbalance) (QCM(Quartz Crystal Microbalance)을 이용한 Betaine 양쪽성 계면활성제의 등전점 측정)

  • Kim, Ji Sung;Park, Jun Seok;Lim, Jong Choo
    • Korean Chemical Engineering Research
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    • v.47 no.1
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    • pp.31-37
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    • 2009
  • A zwitterionic surfactant shows not only detergency but also mildness effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH variations of the aqueous solution. In this study, physical properties of betaine surfactant such as CMC, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was performed. Also dual function characteristics of betaine zwitterionic surfactant were investigated by measuring an isoelectric point using QCM(quartz crystal microbalance) and zeta potential measurement. The CMC of betaine surfactant was near $10^{-4}mol/L$ and the surface tension at CMC was about 32 mN/m. The interfacial tension between 1 wt% aqueous solution and n-decane measured by spinning drop tensiometer at pH 2~10 resulted in an increase in interfacial tension until pH 5 and a decrease with pH after 5 and equilibration time showed the similar trend with an increase in pH. The isoelectric point of betaine surfactant measured by QCM experiment was found to exist between 3.0 and 3.3, which is the same as the result determined by zeta potential measurement.