Piezo-quartz systems

Hence the respective flow fields can be exactly calculated from the Navier Stokes equations, at least for low frequencies, i. e. laminar flows. This is not the case for linear oscillations at either low frequencies, i. e. the linear spring in gas system [3.1], or high frequencies, namely piezo-quartz systems bearing sorbent samples [5.10] or oscillating rod systems (SETARAM). Also at high frequencies the state of the sorbate phase may become transient , i. e. deviate considerably from a thermodynamic equilibrium state. 

Fig. 2. Measuring set-up (A) photograph of the piezoelectric device and flow system, the inset shows the cell holding the quartz sensor (B) sample QCM sensor with 10 MHz base frequency (as used throughout the described experiments) (C) cross-section through the piezo-cell showing the two rubber O-rings holding the quartz plate, only one side of the sensor is in contact with the fluid (D) cross-section of the cell used for combined piezoelectric and amperometric measurements, the lid also hold a titanium wire electrode and the Ag/AgCI reference electrode.

The components of a TS system are shown in Figure 11.39 (130). A resonance stethoscope is used to transmit crystalline vibrations in the sample to the audio frequency range where they are converted to electrical signals by use of a piezo-electric crystal. The stethoscope is constructed of quartz, which, because of its high Q value, operates mechanically both as a tuned pick-up sensor and as a self-exciting resonator. The unit incorporates a sample-holder head shaped as an acoustic transformer and fitted with a transmitter rod that mechanically matches the piezo-electric cell fixed on a heavy recoil... 

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