Microscopy and viscometry of blood flowing under uniform shear rate(rheoscopy)

¹ Departments of Medicine, Harvard Medical School and Peter Bent Brigham Hospital, Boston, Massachusetts 02115; and Block Engineering, Cambridge, Massachusetts 02139

Transparent cone and plate in a Wells-Brookfield LVT viscometer allow direct microscopic observation ( x 60–400 magnification) of blood flowing under specific rates of shear (0.6–1,380 set^–1) while simultaneously measuring shear stress. The viscometer is placed on the stage of an inverted microscope; observation in bright-field and dark-field illumination is made through a thin optical quartz inserted in the plate. The range of shear rates is extended by the use of different cone angles and can be adapted to any desired level by driving the viscometer motor with a sine-wave generator with variable output. The use of the instrument confirmed recent theories about the role of reversible red cell aggregation upon the rheology of blood at low shear rates. The influence of quantified flow forces on reversible red cell aggregation and irreversible platelet aggregation can be examined directly.

Submitted on August 5, 1968