Determination of cell elasticity through hybrid ray optics and continuum mechanics modeling of cell deformation in the optical stretcher

Andrew Ekpenyong, Carolyn L. Posey, Joy L. Chaput, Anya K. Burkart, Meg M. Marquardt, Timothy J. Smith, Michael G. Nichols

Research output: Contribution to journalArticle

19 Scopus citations


The optical stretcher is a dual-beam trap capable of stretching individual cells. Previous studies have used either ray- or wave-optical models to compute the optical pressure on the surface of a spherical cell. We have extended the ray-optics model to account for focusing by the spherical interface and the effects of multiple internal reflections. Simulation results for red-blood cells (RBCs) show that internal reflections can lead to significant perturbation of the deformation, leading to a systematic error in the determination of cellular elasticity. Calibration studies show excellent agreement between the predicted and measured escape force, and RBC stiffness measurements are consistent with literature values. Measurements of the elasticity of murine osteogenic cells reveal that these cells are approximately 5.4 times stiffer than RBCs.

Original languageEnglish
Pages (from-to)6344-6354
Number of pages11
JournalApplied Optics
Issue number32
Publication statusPublished - Nov 10 2009


All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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