Dr Andrew E. Ekpenyong

Associate Professor of Physics. BPhil (Rome), BD (Rome), MS (Physics, Creighton, USA), PhD (Physics, Cambridge, UK)



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Dr Andrew Edet Ekpenyong

Associate Professor of Physics


Curriculum vitae



Office Phone: +14022802208


Physics

Creighton University

2500 California Plaza,
Omaha,
NE 68178,
USA




Dr Andrew E. Ekpenyong

Associate Professor of Physics. BPhil (Rome), BD (Rome), MS (Physics, Creighton, USA), PhD (Physics, Cambridge, UK)



Office Phone: +14022802208


Physics

Creighton University

2500 California Plaza,
Omaha,
NE 68178,
USA



Comparison of stresses on homogeneous spheroids in the optical stretcher computed with geometrical optics and generalized Lorenz-Mie theory.


Journal article


Lars Boyde, Andrew E. Ekpenyong, G. Whyte, J. Guck
Applied Optics, 2012

Semantic Scholar DOI PubMed
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Cite

APA   Click to copy
Boyde, L., Ekpenyong, A. E., Whyte, G., & Guck, J. (2012). Comparison of stresses on homogeneous spheroids in the optical stretcher computed with geometrical optics and generalized Lorenz-Mie theory. Applied Optics.


Chicago/Turabian   Click to copy
Boyde, Lars, Andrew E. Ekpenyong, G. Whyte, and J. Guck. “Comparison of Stresses on Homogeneous Spheroids in the Optical Stretcher Computed with Geometrical Optics and Generalized Lorenz-Mie Theory.” Applied Optics (2012).


MLA   Click to copy
Boyde, Lars, et al. “Comparison of Stresses on Homogeneous Spheroids in the Optical Stretcher Computed with Geometrical Optics and Generalized Lorenz-Mie Theory.” Applied Optics, 2012.


BibTeX   Click to copy

@article{lars2012a,
  title = {Comparison of stresses on homogeneous spheroids in the optical stretcher computed with geometrical optics and generalized Lorenz-Mie theory.},
  year = {2012},
  journal = {Applied Optics},
  author = {Boyde, Lars and Ekpenyong, Andrew E. and Whyte, G. and Guck, J.}
}

Abstract

We present two electromagnetic frameworks to compare the surface stresses on spheroidal particles in the optical stretcher (a dual-beam laser trap that can be used to capture and deform biological cells). The first model is based on geometrical optics (GO) and limited in its applicability to particles that are much greater than the incident wavelength. The second framework is more sophisticated and hinges on the generalized Lorenz-Mie theory (GLMT). Despite the difference in complexity between both theories, the stress profiles computed with GO and GLMT are in good agreement with each other (relative errors are on the order of 1-10%). Both models predict a diminishing of the stresses for larger wavelengths and a strong increase of the stresses for shorter laser-cell distances. Results indicate that surface stresses on a spheroid with an aspect ratio of 1.2 hardly differ from the stresses on a sphere of similar size. Knowledge of the surface stresses and whether or not they redistribute during the stretching process is of crucial importance in real-time applications of the stretcher that aim to discern the viscoelastic properties of cells for purposes of cell characterization, sorting, and medical diagnostics.


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