Large deformation of living cells using laser traps

We present experimental results of large deformation of human red blood cells subjected to direct stretching by optical tweezers, The maximum external force imposed on the cell is in excess of 400 pN. A three-dimensional computational simulation of the biconcave cell membrane is also performed to extract the large deformation elastic properties from the experimental results obtained during loading Lis well as upon relaxation of the load. Different constitutive formulations of the cell membrane with its underlying spectrin network are explored in the computational simulations in an attempt to investigate the mechanical response and to compare the results so obtained with those derived from other independent experimental techniques. These results demonstrate new capabilities in the use of optical tweezers for study of cell deformation at large strains and provide a framework to explore possible effects of different loading configurations. disease states, chemical factors and environment on the large deformation characteristics of biological cells. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.