Piezoelectric viscometer

A method of determining the viscosity of a fluid sample using a piezoelectric device consisting of the following steps:

• (a) vibrating a piezoelectric driver that is mechanically linked to, but electrically isolated from, a piezoelectric receiver having a probe attached thereto, by supplying an AC voltage to said piezoelectric driver;
• (b) setting said AC voltage near the resonant frequency of said piezoelectric receiver;
• (c) first immersing said probe in a first calibration fluid of known high viscosity;
• (d) zeroing an output signal from said piezoelectric receiver using offset gain means;
• (e) second immersing said probe in a second calibration fluid of known low viscosity;
• (f) maximizing said output signal from said piezoelectric receiver using gain amplifier means;
• (g) third immersing said probe in said fluid sample;
• (h) recording said output signal from said piezoelectric receiver;
• and
• (i) correlating said recorded signal with said viscosities of said first and second calibration fluids to give said viscosity of said fluid sample.

A method of determining the temperature of a fluid sample having a known temperature-viscosity curve, using a piezoelectric device consisting of the following steps:

• (a) vibrating a piezoelectric driver that is mechanically linked to, but electrically isolated from, a piezoelectric receiver having a probe attached thereto, by supplying an AC voltage to said piezoelectric driver;
• (b) setting said AC voltage near the resonant frequency of said piezoelectric receiver;
• (c) calibrating said piezoelectric device using a first calibration fluid of known high viscosity, and a second calibration fluid of known low viscosity, said known temperature-viscosity curve having viscosities within the range defined by said first and second calibration fluids;
• (d) immersing said probe in said fluid sample;
• (e) recording an output signal from said piezoelectric receiver;
• (f) first correlating said output signal with viscosity of said fluid sample;
• and
• (g) second correlating said viscosity of said fluid sample to said temperature of said fluid.

A device for measuring the viscosity of a fluid comprising:

• a base;
• a piezoelectric driver anchored to, but electrically isolated from, said base;
• a piezoelectric receiver mechanically linked to, but electrically isolated from, said piezoelectric driver, for receiving vibrations therefrom;
• a probe mounted essentially perpendicularly to said piezoelectric receiver, for immersion in said fluid;
• an AC voltage source electrically connected to said piezoelectric driver, whereby said piezoelectric driver vibrates and transmits said vibrations to said piezoelectric receiver;
• means for receiving output signals from said piezoelectric receiver as vibrations are received from said piezoelectric driver, said output signal giving said viscosity of said fluid;
• and
• said piezoelectric driver, said piezoelectric receiver, and said probe each having first and second ends, said first end of said piezoelectric driver being anchored to said base, said second end of said piezoelectric driver being bonded to said first end of said piezoelectric receiver, and said second end of said piezoelectric receiver being bonded to said first end of said probe, said probe further having temperature measuring means at said second end thereof.