Type of accessories
Quartz Crystal Microbalance A20/F20
Acoustic sensing principle
The acoustic sensing principle is based on the precise detection of changes on the properties of an acoustic (mechanical) wave traveling through the bulk (QCM-AWS, HFF-AWS) or the surface (LOVE-AWS) of the acoustic wave sensor.
QCM-AWS sensors consist of a thin piece of quartz confined between a pair of metal-based electrodes. An alternating current applied to the quartz crystal induces mechanical oscillations on the quartz due to the piezoelectric effect. A wave is generated and propagated through the sensor and the films attached to it.
The Quartz crystal microbalance is a mass-sensitive detector based on frequency changes of an oscillating quartz crystal. The oscillation frequency of the crystal
is proportional to the mass of the crystal, as well as solution properties near the surface (including viscosity, density, temperature, and compression waves).
The resonance frequency of this wave depends on the oscillating mass of the sensor and its adhering layers. When a thin film is attached to the sensor, the properties of the wave change as well, modifiying the resonance frequency and amplitude. If the film is thin and rigid, the decrease in frequency is proportional to the mass of the film. In this way, the QCM works in the so-called gravimetric regime and the mass of the film can be calculated using the well-known Sauerbrey equation. If the film is not rigid, the measurement of the damped resonance enables the measurement of the viscoelastic changes of the film, allowing the characterization of the QCM working in the non-gravimetric regime.
A mass increase results in a frequency decrease. Sauerbrey was the first to provided a description and experimental verification of the mass/frequency relationship between foreign layers firmly attached
to the quartz crystal resonator(1)(2).
(1): G. Sauerbrey, Phys. Verh., 1957, 8, 113-114.
(2): G. Sauerbrey, Z. Phys., 1959, 155, 206-222.
The Sauerbrey equation is defined as:
ƒ0: resonant frequency (Hz)
∆ƒ: frequency change (Hz)
∆m: mass change (g)
A: piezoelectrically active crystal area
(area between electrodes, cm²)
ρq: density of quartz (?q = 2.648 g/cm³)
µq: shear modulus of quartz for AT-cut crystal
(µq = 2.947×1011 g/(cm.s²))
|Sensor||QCM 14 mm wrapped||QCM 1’’ wrapped||QCM 1’’ wrapped|
|AW-GBQ01Q (Glove box)|
|AW-GBQ02Q (Glove box)|
Reference and counter electrodes have to be purchased separately (except for eQCM flow cells where the Pt plate counter electrode is integrated in the lid of the cell).. Compatible counter and reference electrodes are shown in the following table:
|In-batch eQCM cells||RE-1B|
|Pt wire 23 cm coiled|
|Flow eQCM cells||RE-1S|
|Pt disk integrated in the cell lid|
|Operation modes||High Resolution Mode|
Number of cell modules
|QCM, HFF-QCM, LOVE|
Up to 4 cell modules
Integrated in the system (Peltier)
|Frequency range||5 MHz – 160 MHz|
|Frequency resolution||1 mHz|
|Frequency stability||± 0.05 ppm, over 0 to 50 °C|
|Frequency accuracy||± 0.1 Hz|
|Remote control and monitoring interface via ethernet|
AWS F20 (optional)
|Up to 4 flow-through modules|
The 4 flow-modules can be operated simultaneously
Standard version of AWS F20 works simultaneously with AWS A20
Built-in thermostatic system for temperature control of liquids
|Remote control and monitoring interface via IP|
|Weight||35 kg with complete 4 module configuration|