Microbalance QMagic EpsilonPi

QCMAGIC: Quartz Crystal Microbalance

The QCMagic modular set-up belongs to the Quartz Crystal Microbalance-based (QCM) instruments. It is manufactured by an Italian Company: Elbatech SRL.

QCM consists of a thin quartz disk with electrodes plated on it: it is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.

The minimum impedance occurs when the thickness of the crystal is a multiple of a half wavelength of the acoustic wave; the resonant oscillation is achieved by including the crystal into an oscillation circuit where the electric and mechanical oscillations are near to the fundamental frequency of the crystal.

QCM consists of a thin quartz disk with electrodes plated on it: it is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface. The minimum impedance occurs when the thickness of the crystal is a multiple of a half wavelength of the acoustic wave; the resonant oscillation is achieved by including the crystal into an oscillation circuit where the electric and mechanical oscillations are near to the fundamental frequency of the crystal.

The fundamental frequency depends on the thickness of wafer, its chemical structure, its shape and its mass; oscillation frequency is influenced by thickness, density and shear modulus of the quartz and physical properties of the adjacent medium like density and viscosity of air or liquid. As shown by Sauerbrey in 1959, changes in resonant frequency are simply related to the mass accumulated on the crystal by the following equation:

formula Saurbrey

where:
?q and ?q are the density and the viscosity of the quartz, n is the overtone number, f0 is the basic oscillator frequency of the quartz and m is the mass adsorbed on the surface per unit/area.
For an AT-cut quartz crystal ?f = – 2.26 x10-6 f0 2 ?m

QCMagic is a high precision measuring instrument featuring excellent performance in the recovery of the oscillation frequency of a working quartz crystal.The system is interfaced to the driving PC by means of the USB port. One single Base Unit can drive up to 4 oscillator modules, thus allowing

formula Nomura

to operate with up to 4 independent quartz crystals (or with two pairs of working/reference crystals). QCMagic can be equipped with low-volume static or flow-through reaction chambers, which house the oscillating crystal; fitting the transducer into the different type of cells is rapid and convenient. QCMagic makes use of a precision internal reference crystal, used as a timebase comparator. Depending on the frequency of this internal timebase, each Unit can be tuned to work with a specific working crystal, choosen between 1 and 10 MHz. The Oscillator Modules are connected to the Base Unit by means of a RJ45 cable carrying both power supply and signals.

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