Papers Published

  1. Needham, D. and Hochmuth, R.M., Rapid flow of passive neutrophils into a 4 μm pipet and measurement of cytoplasmic viscosity, Journal of Biomechanical Engineering, Transactions of the ASME, vol. 112 no. 3 (1990), pp. 269 - 276 .
    (last updated on 2007/04/06)

    Neutrophils from five different individuals are isolated with a density separation technique. A total of 151 unactivated (passive) cells are rapidly aspirated at constant suction pressure and at room temperature into a pipet with a diameter of 4 μm. A theory based on the flow of a Newtonian liquid from either a hemisphere or a spherical segment into a cylinder is used to model the entry process. Both theory and experiment show that during most of the entry process the leading edge of the cell moves at a nearly constant velocity with a rapid acceleration at the end. The results and those of Evans and Yeung at lower aspiration pressures indicate that the complex cytoplasm inside unactivated neutrophils behaves as a nearly Newtonian fluid with a viscosity on the order of 102 Pa·s over almost a two order of magnitude range in aspiration pressure and, thus, rate of deformation.

    Biomechanics;Flow of Fluids - Newtonian;Biomedical Engineering - Cytology;Viscosity - Measurements;Separation;