Quartz crystal microbalance application

Z. X. Lin and M. D. Ward, The role of longitudinal-waves in quartz-crystal microbalance applications in liquids, y4na/. Chem., 67,685-693 (1995). 

Ward, M. D., Principles and applications of the electrochemical quartz crystal microbalance, in Physical Electrochemistry, I. Rubenstein, Ed., Marcel Dekker, New York, 1995, p. 293. 

The quartz crystal microbalance has a long history of application as a means of determining film thickness in vacuum deposition techniques and more recently as a means of detecting trace constituents in the gas phase. In essence, it is an extremely sensitive sensor capable of measuring mass changes in the nanogram range. 

The first application of the quartz crystal microbalance in electrochemistry came with the work of Bruckenstein and Shay (1985) who proved that the Sauerbrey equation could still be applied to a quartz wafer one side of which was covered with electrolyte. Although they were able to establish that an electrolyte layer several hundred angstroms thick moved essentially with the quartz surface, they also showed that the thickness of this layer remained constant with potential so any change in frequency could be attributed to surface film formation. The authors showed that it was possible to take simultaneous measurements of the in situ frequency change accompanying electrolysis at a working electrode (comprising one of the electrical contacts to the crystal) as a function of the applied potential or current. They coined the acronym EQCM (electrochemical quartz crystal microbalance) for the technique. 

I. Vikholm, W.M. Albers, H. Valimaki, and H. Helle, In situ quartz crystal microbalance monitoring of Fab-fragment binding to hnker lipids in a phosphatidylcholine monolayer matrix application to immunosensors. Thin Solid Films 327, 643-646 (1998). 

In Applications of Piezoelectric Quartz Crystal Microbalances Lu, C. Czanderna, A., Eds. Elsevier New York, 1984. 

An application of an electrochemical quartz crystal microbalance (EQCM) in the study of the A11/HCIO4 system shows that even at a potential about 0.5 V more negative than the onset of AuO formation (the so-called preoxide region), the resonant frequency of the Au-covered quartz crystal decreases as that of the surface mass increases. A comparison of a voltammogram with the potential dependence of the micro-balance frequency for an Au electrode is shown in Figs. 6a and 6b. 

Fig. 3.5. Silicon etch rate as measured with a quartz crystal microbalance as a function of the bias voltage applied to the silicon surface in CF4 and Ar glow discharges. The discharge intensity was not significantly influenced by the application of the negative voltage to the silicon surface...

Buttry DA (1991) Application of Quartz Crystal Microbalance to Electrochemistry. In Bard AJ (ed) Electroanalytical chemistry, vol 17. Marcel Dekker, New York, p 1... 

C. Lu, A. Czanderna (eds.), Applications of Piezoelectric Quartz Crystal Microbalances, Elsevier, Amsterdam, 1984. 

This is the correct name for most popular mass sensors, although they are better known as Quartz Crystal Microbalances (QCMs). A piezoelectric crystal vibrating in its resonance mode is a harmonic oscillator. For microgravimetric applications, it is necessary to develop quantitative relationships between the relative shift of the resonant frequency and the added mass. In the following derivation, the added mass is treated as added thickness of the oscillator, which makes the derivation more intuitively accessible. 

Ho, M.H. (1984) Application of quartz crystal microbalances in aerosol mass measurement. 

Although less common, some third-order chemical sensors have found significant applications not only in sensing but also in research. One such example is Electrochemical Quartz Crystal Microbalance (EQCM). With EQCM, an electrochemical experiment can be performed in its inherently large experimental space, that is, various electrochemical waveforms, impedance analysis, gating, and different mass loading. As the dimensionality of the experiment is increased, so is its information content. 

Alternate anti-vs procoagulant activity of human whole blood on a LbL assembly between chitosan and dextran sulfate has been achieved [149,150]. Furthermore, the technique permits the formation of biodegradable nanostructures with nanometer-order thickness on surfaces, which is an important requirement for biomedical applications. The alternating enzymatic hydrolysis of a LbL assembly formed from chitosan and dextran sulfate by chitosanase was demonstrated via measurements with a quartz crystal microbalance (QCM) [151]. The hydrolysis of the assembly was clearly dependent on the surface component. The hydrolysis of the assembly with the dextran sulfate surface was saturated within 10 min and was much faster than the hydrolysis of the assembly with the chitosan surface, although chitosanase can hydrolyse chitosan (Fig. 14). 

Analytical Applications of the Electrochemical Quartz Crystal Microbalance... 

The application of novel in situ spectroscopic techniques for the study of Li electrodes in solutions should also be acknowledged. These include FTIR spectroscopy [108], atomic force microscopy (AFM) [109], electrochemical quartz crystal microbalance (EQCM) [110], Raman spectroscopy [111], and XRD [83],... 

Kinetic applications of the electrochemical quartz crystal microbalance Ch. 12... 

---