instrumental analysis (laboratory-based analysis), sensor placement approach,
model-based event detection, microfluidic devices, spectroscopic approach, and
biosensors. Selecting a certain detection technique is strongly dependent on the
purpose of the analysis, whether it requires quantitative, qualitative, or hybrid
measurements. Biological and chemical sensors have been in great demand for use
in water monitoring technology, and they appear to be suitable for device integration
and commercialization.
Previously, the detection of water contaminants was often conducted manually in
water laboratory facilities [1]. At the laboratory level, analyses are usually carried
out by skillful personnel using high-end and cutting-edge technologies. Conventionally, multiple fermentation tube technique [2], filtration method [3], DNA
amplification [4], fluorescence in-situ hybridization (FISH) techniques [5, 6], capillary electrophoresis [7, 8], field-flow fractionation [9], chromatography [10], mass
spectrometry [11], and electrochemical-based device [12] are the most commonly
used instruments. The overall benefits of laboratory-based analytical methods have
been recognized since a long time, but recent studies have shown that they are not
efficient for on-site monitoring applications. With the technological advancements in
analytical chemistry, new techniques have been developed through the introduction
of advanced spectroscopy [13] and water quality sensors [14–16].
High sensitivity and real-time monitoring of mass changes on the sensor crystal
make quartz crystal microbalance (QCM) a very attractive technique for a large
range of applications. The development of QCM systems for use in fluids or with
viscoelastic deposits has dramatically increased the interest for this technique.
A major advantage of the technique used for liquid systems is that it allows for a
label-free detection of molecules. QCM is capable of measuring mass changes as
small as a fraction of a monolayer of atoms. QCM crystals are becoming a good
alternative analytical method in a great deal of applications such as biosensors,
analysis of biomolecular interactions, study of bacterial adhesion at specific interfaces, pathogen and microorganism detection, study of polymer film–biomolecule or
cell–substrate interactions, immunosensors, and extensive use in fluids and polymer
characterization and electrochemical applications among others. QCM is used also
in gaseous environments, e.g., as gas and humidity sensors and for the detection of
aerosols [17], but its main capability consists in providing real-time monitoring of
contaminants in process, recycle, and waste water; groundwater quality monitoring;
detection of contaminants in streams, lakes, and water supplies; monitoring dumping
in off-shore waterways [18].
2 Theory and Modeling of QCM Data
2.1 Sauerbrey’s Equation: Rigid Mass
The first quantitative analysis of using quartz crystal resonators as mass sensors was
developed by Sauerbrey in 1959 [19].
Quartz Crystal Microbalance Sensors: New Tools for the Assessment of. . .
317
model-based event detection, microfluidic devices, spectroscopic approach, and
biosensors. Selecting a certain detection technique is strongly dependent on the
purpose of the analysis, whether it requires quantitative, qualitative, or hybrid
measurements. Biological and chemical sensors have been in great demand for use
in water monitoring technology, and they appear to be suitable for device integration
and commercialization.
Previously, the detection of water contaminants was often conducted manually in
water laboratory facilities [1]. At the laboratory level, analyses are usually carried
out by skillful personnel using high-end and cutting-edge technologies. Conventionally, multiple fermentation tube technique [2], filtration method [3], DNA
amplification [4], fluorescence in-situ hybridization (FISH) techniques [5, 6], capillary electrophoresis [7, 8], field-flow fractionation [9], chromatography [10], mass
spectrometry [11], and electrochemical-based device [12] are the most commonly
used instruments. The overall benefits of laboratory-based analytical methods have
been recognized since a long time, but recent studies have shown that they are not
efficient for on-site monitoring applications. With the technological advancements in
analytical chemistry, new techniques have been developed through the introduction
of advanced spectroscopy [13] and water quality sensors [14–16].
High sensitivity and real-time monitoring of mass changes on the sensor crystal
make quartz crystal microbalance (QCM) a very attractive technique for a large
range of applications. The development of QCM systems for use in fluids or with
viscoelastic deposits has dramatically increased the interest for this technique.
A major advantage of the technique used for liquid systems is that it allows for a
label-free detection of molecules. QCM is capable of measuring mass changes as
small as a fraction of a monolayer of atoms. QCM crystals are becoming a good
alternative analytical method in a great deal of applications such as biosensors,
analysis of biomolecular interactions, study of bacterial adhesion at specific interfaces, pathogen and microorganism detection, study of polymer film–biomolecule or
cell–substrate interactions, immunosensors, and extensive use in fluids and polymer
characterization and electrochemical applications among others. QCM is used also
in gaseous environments, e.g., as gas and humidity sensors and for the detection of
aerosols [17], but its main capability consists in providing real-time monitoring of
contaminants in process, recycle, and waste water; groundwater quality monitoring;
detection of contaminants in streams, lakes, and water supplies; monitoring dumping
in off-shore waterways [18].
2 Theory and Modeling of QCM Data
2.1 Sauerbrey’s Equation: Rigid Mass
The first quantitative analysis of using quartz crystal resonators as mass sensors was
developed by Sauerbrey in 1959 [19].
Quartz Crystal Microbalance Sensors: New Tools for the Assessment of. . .
317