Viscosity measuring method
AssigneesStc.Unm, Senior Scientific, LLC
InventorsNatalie L. Adolphi, Edward R. Flynn, Howard Bryant, Kimberly Butler
Life of this patent
Estimating the term…
Abstract
A method for measuring the average viscosity of a test fluid uses calibrated magnetic nanoparticles, with certain chosen hydrodynamic diameters and actual lateral dimensions (e.g. diameters), that are mixed into a small volume of the test fluid and a single magnetic relaxation curve measurement to provide data for viscosity determination. The distribution of hydrodynamic particle sizes of an ensemble of magnetic nanoparticles that are magnetically blocked at room temperature can be determined. Modifications of the method can be used to determine the distribution of viscosities in a complex fluid at the sub-microscopic level providing a novel type of viscosity measurement.
Claims15
A method of measuring the average viscosity of a test fluid, comprising introducing magnetic nanoparticles in the test fluid, subjecting the test fluid to a magnetic field pulse, then measuring magnetic relaxation of the magnetic nanoparticles in the test fluid after termination of the magnetic field pulse, determining a decay time constant of the nanoparticles in the test fluid, determining a calibrated decay time constant of like nanoparticles in a calibration fluid, and determining viscosity of the test fluid using the time constants and the known viscosity of the calibration fluid.
A method of determining distribution of hydrodynamic particle sizes of magnetic nanoparticles by relaxometry measurement, comprising introducing magnetic nanoparticles having a particle lateral dimension selected large enough to reduce or eliminate Neel relaxation effects on the relaxometry measurement into a control fluid, subjecting the control fluid to a magnetic field pulse, and measuring a relaxation curve, which is the sum of one or more single exponential decays, for the nanoparticles in the control fluid, and using the measured relaxation curve to determine distribution of relaxation time constants, which are proportional to the distribution of hydrodynamic particle diameters.
Dependencies are inferred from the claim text.