Measurement, compensation and control of equivalent shear rate in acoustic wave sensors
AssigneeBiode, Inc.
InventorJeffrey C. Andle
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Abstract
A method for measuring viscosity and shear rate at which the measurement is performed is provided, by utilizing an acoustic wave sensor, and calculating the shear rate as a function of the characteristic rate of quartz movement in response to a given power transmitted to a fluid, and the viscosity of the fluid. Related aspects of the invention provide for methods for controlling the shear rate at which a viscosity measurement is performed, and characterizing viscoelastic fluids at a plurality of shear rates.
Claims34
A method for measuring shear rate at which the viscosity of a fluid is measured utilizing an acoustic wave device, the acoustic wave device having an input and an output transducers, and having a characteristic relationship between input power, output power, and an acoustic wave amplitude at a selected region between the input and output transducer, the acoustic wave device being coupled to the measured fluid, the method comprising the steps of:
- applying a predetermined power Pin of a harmonic signal having a frequency ω to the input transducer, to impart an acoustic wave at the selected region;
- measuring output power level Pout at the output transducer;
- using the characteristic relationship, and the input and output power levels, calculating the amplitude of the average acoustic wave imparted to the fluid;
- measuring viscosity of the fluid to obtain a measured viscosity at the selected region;
- and
- calculating the shear rate of the fluid at the selected region by using the frequency, the viscosity measurement, and the acoustic wave amplitude.
A method for measuring the shear rate at which the viscosity of a fluid is measured using an acoustic wave device having an input and an output transducers, and being coupled to the fluid for imparting a signal thereto, the method comprising the steps of:
- imparting a signal of a selected input power level into the input transducer, and measuring an output power level of the harmonic signal from the output transducer;
- measuring the viscosity of the fluid;
- calculating the average penetration depth of the signal imparted to the fluid using the input power level, the output power level, the separately-known density, and characteristic of the acoustic wave device construction, to derive the average amplitude of the wave imparted to the fluid;
- and
- calculating the shear rate of the viscosity measurement using the measured viscosity of the fluid, and the calculated penetration depth.
Dependencies are inferred from the claim text.