ABSTRACT
We calculated the three-dimensional optical stress distribution and the resulting deformation on a biconcave human red blood cell (RBC) in a pair of parallel optical trap. We assumed a Gaussian intensity distribution with a spherical wavefront for each trapping beam and calculated the optical stress from the momentum transfer associated with the reflection and refraction of the incident photons at each interface. The RBC was modelled as a biconcave thin elastic membrane with uniform elasticity and a uniform thickness of 0.25 µm. The resulting cell deformation was determined from the optical stress distribution by finite element software, Comsol Structure Mechanics Module, with Young's modulus (E) as a fitting parameter in order to fit the theoretical results for cell elongation to our experimental data.
Subject(s)
Cell Shape/radiation effects , Erythrocytes/cytology , Erythrocytes/radiation effects , Models, Biological , Optical Tweezers , Pressure , Cell Shape/physiology , Computer Simulation , Elastic Modulus , Erythrocytes/physiology , Humans , Normal Distribution , PhotonsABSTRACT
We report the experimental demonstration of optical stretching of individual bio-concave human red blood cells (RBCs) with one-dimensional jumping optical tweezers. We trapped a RBC in isotonic buffer solution in a conventional stationary single-beam gradient-force optical trap and discretely scanned the trapping beam with an acousto-optic modulator such that the focal point of the trapping beam jumped back-and-forth between two fixed points. At the jumping frequency on the order of a 100 Hz and higher, and the jumping distance in the range of a few microns, the bi-concave RBC was stably trapped and stretched. The elongation of the stretched RBC was measured as a function of the beam-scanning amplitude, and the experimental results were explained qualitatively by a theoretical model.
Subject(s)
Micromanipulation/methods , Models, Cardiovascular , Optical Tweezers , Cells, Cultured , Computer Simulation , Elasticity , Humans , Stress, MechanicalABSTRACT
A cesium 6S(1/2) --> 8S(1/2) two-photon-transition (TPT)-stabilized 822.5 nm diode laser is reported for the first time to our knowledge. Allan deviation of 4.4 x 10(-13) (60 s) was achieved, and the possible systematic errors were evaluated as smaller than 2 kHz. We demonstrate that the cesium TPT-stabilized diode laser could be a reliable frequency reference at 822.5 nm wavelength.
