Dynamic Deformation of Soft Particle in Dual-trap Optical Tweezers

Y. Sheng[1], S. Rancourt-Grenier[1], P. Bareil[1], P. Duval[1], M. Wei[2], A. Chiou[2], and J. Bai
[1]University Laval, Quebec, QC, Canada
[2]National Yang-Ming University, Taipei, Taiwan
Published in 2010

A dual-trap optical tweezers is used for deforming the red blood cell (RBC) in suspension and studying its elasticity. The 3D deformation of the cells was computed with the elastic membrane theory. The calculated deformation can fit to experimental data resulting in cell’s elasticity coefficient. The static approach is valid only for small deformation (5-10%). For a large deformation such as that of the RBC, we consider re-distribution of the radiation stress on the morphologically deformed cell. This stress re-distribution in turn induces subsequent deformation of the deformed cell and new stress re-distribution. The recursive process continues until a final equilibrium state is achieved. This iterative computation was implemented with the finite element method using the COMSOL Multiphysics models. The deformation results can fit to the experimental data for cell’s deformation up to 20%.