Patent ID: 6564618
Filing Date: 2003-05-20
Classification: A61B,G01N

Abstract:
An apparatus for determining the viscosity of a fluid over plural shear rates using a decreasing pressure differential, said apparatus comprising:a fluid source elevated at a first reference position above a horizontal reference position; a valve in fluid communication with said fluid source via a first port for controlling a flow of fluid from said fluid source; a flow restrictor having a first end and a second end, said first end being in fluid communication with a second port of said valve, said flow restrictor having some known dimensions and being positioned at said horizontal reference position; a lumen having one end in fluid communication with a third port of said valve and another end being exposed to atmospheric pressure, said lumen being positioned at an angle greater than zero degrees with respect to said horizontal reference position; a processor coupled to said valve for controlling said valve to permit the flow of fluid into said lumen to form a column of fluid therein whereby a pressure differential is formed between a level of said column of fluid and said flow restrictor, said processor also being arranged for operating said valve to isolate said lumen from said fluid source and for coupling said flow restrictor and said lumen together to generate a falling column of fluid in said lumen, said falling column of fluid moving through said lumen, through said valve and said flow restrictor at a first shear rate caused by said pressure differential, said movement of fluid causing said pressure differential to decrease from said first shear rate for generating said plural shear rates; a sensor for detecting the movement of said falling column of fluid, said sensor generating data relating to the movement of said falling column of fluid over time; an electric/magnetic field generator for subjecting said flow restrictor to an electric/magnetic field when the fluid is flowing therein; and said processor, also coupled to said sensor, for calculating the viscosity of the fluid over a range of plural shear rates based on said data relating to the movement of said falling column of fluid over time and said some known dimensions.