Theory and design of disposable clinical blood viscometer.
A disposable clinical whole blood viscometer which can produce viscosity measures over a wide range of shear rates in a single rapid determination has been developed and is currently under test. The design is based upon the time varying flow of blood through a capillary. The flow is driven by the pressure in a fixed volume air chamber and transmitted to the sample through a compliant membrane. The time varying pressure in the air chamber is measured by a suitable transducer. The instantaneous shear stress of the blood in the capillary is proportional to the air pressure, while the instantaneous shear rate is proportional to the pressure-time derivative. Proper design ensures that the system operates as a first order dynamic system with flow resistance entirely determined by the nonlinear sample viscosity. By constructing the air chamber in two parts coupled by a quick disconnect fitting the design can allow for the blood-containing part of the instrument to be discarded, eliminating handling and cleaning of blood contacted components. The entire determination is completed in less than a minute, so that anticoagulants are not necessary. Tests on a prototype show that the instrument gives results in excellent agreement with those obtained on a cone-plate rheogoniometer.
Litt
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KDL Technologies, Inc., Philadelphia, Pennsylvania.
Kron
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Litt
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D001809:Blood Viscosity; D002196:Capillaries; D004209:Disposable Equipment; D006403:Hematologic Tests / Q000295:instrumentation*; D012212:Rheology