A precision method to measure average viscoelastic parameters of erythrocyte populations

Suspensions of erythrocytes in media of low conductivity are subjected to homogenous high frequency electric fields (1 MHz, approximately 10 to 40 kV/m). The resulting transient deformation of the cells is measured by laser light diffraction. Employing a viscoelastic model of the erythrocyte membrane, relative values of membrane shear modulus and response time can currently be determined to within 7% or better. With a measurement time of one minute the average values of some 10⁵ cells can be obtained. As a test of the method, osmotic swelling and deflation of the cells and crosslinking their membrane skeleton by diamide are used to alter the viscoelastic properties of the erythrocytes.