Scanning electrochemical mass sensitivity mapping of the quartz crystal microbalance in liquid media

A. C. Hillier, Michael Ward

Research output: Contribution to journalArticle

Abstract

The mass sensitivity distribution of the quartz crystal microbalance, denoted S(r,θ), was determined in situ for plano-plano and plano-convex AT-cut quartz resonators. The method involved measuring the frequency change associated with localized mass deposits created by electrochemical deposition using a scanning microelectrode in close proximity to the QCM electroded surface. Complete mathematical descriptions of S(r,θ) were obtained from the measured data under conditions commonly encountered in QCM experiments. Our experimental results suggest that crystal contouring increases sensitivity toward the resonator center while reducing the extent of field fringing. Increasing solution viscosity reduces the sensitivity to mass changes in the center of the resonator and increases field fringing, while an increase in the rigid mass within the electroded area increases the sensitivity in the center of the resonator. Under most conditions, S(r,θ) appeared dependent upon electrode geometry and tab placement but exhibited negligible dependence upon the crystal orientation with respect to the shearing axis. The integral sensitivity, as determined by integration of the sensitivity maps, was significantly less than that predicted by the Sauerbrey equation. These results demonstrate that detailed understanding of the sensitivity distribution is important when the QCM is used in liquid media, in the presence of nonuniform mass deposits, and under conditions favoring field fringing.

Original languageEnglish (US)
Pages (from-to)2539-2554
Number of pages16
JournalAnalytical Chemistry
Volume64
Issue number21
StatePublished - Nov 1 1992

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Quartz crystal microbalances
Resonators
Scanning
Liquids
Deposits
Quartz
Microelectrodes
Shearing
Crystal orientation
Viscosity
Crystals
Electrodes
Geometry
Experiments

ASJC Scopus subject areas

  • Analytical Chemistry

Cite this

Scanning electrochemical mass sensitivity mapping of the quartz crystal microbalance in liquid media. / Hillier, A. C.; Ward, Michael.

In: Analytical Chemistry, Vol. 64, No. 21, 01.11.1992, p. 2539-2554.

Research output: Contribution to journalArticle

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