IJUP08 - Universidade do Porto
IJUP08 - Universidade do Porto
IJUP08 - Universidade do Porto
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Resonant frequency shift / Hz<br />
Quartz Crystal Microbalance: A Useful Tool As Sensor Of Thin<br />
Films<br />
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J. Borges, C. M. Pereira and F. Silva<br />
Department of Chemistry, Faculty of Science, University of <strong>Porto</strong>, Portugal.<br />
Rua <strong>do</strong> Campo Alegre, 687, 4169-007 <strong>Porto</strong>, Portugal<br />
The quartz crystal microbalance (QCM) is a simple, cost effective, high-resolution mass<br />
sensing technique, based upon the piezoelectric effect [1] . A quartz crystal microbalance<br />
(QCM) is an electromechanical transducer that can produce an electrical signal in response<br />
to inertial and viscoelastic changes of a quartz crystal when a voltage is applied across its<br />
faces [2] . The QCM then measures the frequency of oscillation of the crystal and possesses<br />
a wide detection range. The QCM can detect changes in frequency of the crystal due to<br />
changes in mass deposited on the surface of the crystal. This characteristic contributes for<br />
the development of sensors [3] . Figure 1 shows a typical result obtained in the study on the<br />
deposition of Oleylamine by adsorption at the surface of gold plated quartz crystal using<br />
the QCM-Z500 instrument.<br />
∆f = f (t)<br />
0 500 1000 1500 2000 2500 3000 3500 4000<br />
time / sec<br />
Fundamental<br />
3rd Overtone<br />
5th Overtone<br />
7th Overtone<br />
9th Overtone<br />
11th Overtone<br />
Figure 1. Changes in ∆f<br />
due to the deposition by<br />
adsorption of Oleylamine<br />
at the surface of the gold<br />
plated quartz crystal.<br />
The experimental results will be analyzed in order to characterize the adsorption behaviour<br />
of Oleylamine at gold surfaces and results will be presented regarding the thermodynamics<br />
of the adsorption process.<br />
Acknowledgments:<br />
Financial support from FCT (POCI 2010) and FEDER for the project POCI/QUI/57679/2004 is<br />
gratefully acknowledged. J. Borges acknowledges the project POCI/QUI/57679/2004 for a BI<br />
grant.<br />
References:<br />
[1] Kenneth, A. M., Biomacromolecules, 2003, 4 (5), 1099-1120.<br />
[2] Etchenique, R. A.; Calvo, E. J., Anal. Chem., 1997, 69, 4833-4841.<br />
[3] Pei, Z.; Anderson, H.; Aastrup, T.; Ramström, O., Biosensors and Bioelectronics, 2005, 21, 60-<br />
66.<br />
164
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