Shear rate and hematocrit effects on the apparent diffusivity of urea in suspensions of bovine erythrocytes.

This work aimed to demonstrate a new method to determine diffusivities in blood and to show how urea transport is affected by blood cells. Diffusivities of urea in suspensions of bovine erythrocytes in bovine albumin solutions were determined in a two-layer membraneless microfluidic device as a function of interfacial shear rate and hematocrit. The experiments validated the measurement system at zero hematocrit and provided measurements at finite hematocrits, unobtainable in static systems. Both obstruction of diffusion by unsheared and thus non-rotating cells and augmentation of diffusion by cells rotating in response to shear were demonstrated.