Admittance viscosity

This approach is dedicated to the measurement of hquid viscosity by determining the real part of the sensor admittance at series resonance frequency. According to this concept, one terminal of the sensor is fed with the (constant-level) output of a VCO. The resonator current I is measured by connecting a transimpedance amphfier at the second terminal. Due to the low input impedance of the transimpedance amphfier, the entire VCO output voltage is apphed to the sensor. Parasitic capacitances from the sensor terminals to ground (e.g., due the shielding of the connection cables) are on one side... 

When a quartz resonator is in contact with a viscous liquid, viscous coupling is operative (Figure 2-(b)). The added effect of viscous liquid modifies the equivalent circuit to include both the mass loading density component (Ll), and a resistive viscosity component (RJ of the liquid. The increase of the total value of the resistor (Ri + RJ, results in reducing the radii in admittance circles, which affects the stability of oscillation. The series resonance frequency shifts its value when a QCM is immersed in the liquid. The new resonance frequency due to the increased inductance from the viscous liquid is,... 

Bulk acoustic wave admittance analysis was used to study solvent evaporation during curing. Three characteristic stages were identified in the first stage viscosity increases accompanied by a rapid decrease in diffusion rate in the second stage the film is formed, the... 

Figure 17.2 The effect of increasing viscosity of the fluid on the admittance curves. 1-dimethyl ether 2-water 3-40% aqueous solution of sucrose, 4-50% solution of the...

In Figure 17.2 we present a series of admittance spectra, showing the effect of viscosity and density on the shape of the admittance curves. Different solutions were used, as listed in the caption to this figure. No potential was applied and no electrochemical reaction took place. Adsorption of the solvent or the solute may have taken place, but this would not account for any increase in the width, and to only a small shift in frequency, of the order of a few Hz, while the total shift of the resonance frequency shown is in the range of several kHz. 

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