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The QCM100 is a low cost quartz crystal microbalance system designed
for real-time mass and viscosity measurements in processes occurring
at or near surfaces, or within thin films. It comes with controller,
oscillator electronics, crystal holder, and three quartz crystals.
An external frequency counter and precision voltmeter (not included)
are needed to complete the QCM measurement setup.
The QCM series measure the resonant frequency and resistance of
an AT-cut quartz crystal. The resonant frequency changes as a linear
function of the mass of material deposited on the crystal surface.
The resistance at resonance changes with the viscoelasticity of
the material (film or liquid) in contact with the crystal’s
face.
As a gravimetric instrument, the QCM100 can measure mass ranging
from micrograms to fractions of a nanogram, with detection limits
corresponding to submonolayers of atoms. Measurement of resistance
provides the opportunity to examine the viscosity and elasticity
of films and liquids at or near the crystal surface. This makes
it feasible to observe conformational changes, such as phase transitions,
swelling and cross-linking, in real time. The electronics are specifically
designed to handle heavy loads (up to 5 kΩ)
making these instruments ideal for studies involving lossy films
and highly viscous liquids.
Crystal Oscillator Electronics
The crystal oscillator electronics employ a unique automatic gain
control (AGC) circuit instead of the traditional phase-lock oscillator
(PLO). The AGC provides the quartz crystal resonator with the necessary
gain to overcome viscoelastic losses and achieve series resonance.
It also provides a signal for monitoring the energy dissipated by
the sensor (which is related to the series resonance resistance).
The oscillator will reliably drive crystals with resistance up to
5 kΩ, and will maintain oscillation in
viscous aqueous solutions containing over 88 % glycerol (w/w %).
The controller provides power to the crystal oscillator electronics
and includes a potentiometer for canceling shunt capacitance. Proper
capacitance cancellation is required to assure true series resonance
operation of the crystal oscillator and to eliminate frequency and
resistance errors.
Flow Cell
An axial flow cell adapter (opt.) is available which attaches to
the standard crystal holder. This provides the simplest way to interface
a QCM to a flow injection analysis system.
Quartz Crystals
The QCM100 uses a 5 MHz, 1" diameter, AT-cut quartz crystal.
All crystals are designed for operation in liquids and are available
in a variety of materials.
In the Lab
The QCM100 is a valuable research tool for applications ranging
from pure surface science to biochemistry. Frequency, mass and resistance
measurements can be made in both gas and liquid phase environments.
Quartz crystals can be pre-coated with any thin film material including
organic polymers, hydrogels, composites, ceramics, biomolecules,
bacteria and living cells. This provides unlimited potential for
the development of novel gas and biological sensors.
A QCM100 Quartz Crystal Microbalance is an essential addition to
any biological laboratory. The data from a QCM perfectly complements
that obtained from other techniques such as surface plasmon resonance
(SPR) and atomic force microscopy (AFM), aiding the analysis of
complex biological interactions.
Applications
Selected Literature
Citations of SRS QCM100/200
Immunosensors
Sorption sensors
Moisture analyzers
Particulate monitors
Contamination monitors
Hydrogen absorption on metal films
Bubble formation
DNA and RNA hybridization studies
Antigen-antibody reactions
Protein adsorption
Detection of virus capsids, bacteria, mammalian cells
Biofouling and antifouling
Biomembranes and biomaterials
Cell adhesion
Protein-protein interactions
Self-assembled monolayers (SAMs)
Molecularly imprinted polymers (MIPs)
Langmuir/Langmuir-Blodgett films
Laser ablation, desorption and breakdown studies
MEMs nanomaterials
Intelligent biomaterials
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