Difference between revisions of "Brownian Dynamics of a Sphere Between Parallel Walls"
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To the right is a diagram showing my best interpretation of the apparatus the authors used to make high resolution measurements of the brownian motion of a sphere confined along one dimension by two glass planes 8 microns apart. They positioned a 1 micron sphere in a precise position using an optical trap, then released it to study motion. They imaged with a video microscope at 60 Hz and used particle centroiding to obtain a resolution of 20 nm in x and y. They obtained z information by repeating the experiment releasing the particle from the same location with the microscope focused at differing heights. They measure distance from the wall by running a steady poiseuille flow and observing its effect on the particle velocity. | To the right is a diagram showing my best interpretation of the apparatus the authors used to make high resolution measurements of the brownian motion of a sphere confined along one dimension by two glass planes 8 microns apart. They positioned a 1 micron sphere in a precise position using an optical trap, then released it to study motion. They imaged with a video microscope at 60 Hz and used particle centroiding to obtain a resolution of 20 nm in x and y. They obtained z information by repeating the experiment releasing the particle from the same location with the microscope focused at differing heights. They measure distance from the wall by running a steady poiseuille flow and observing its effect on the particle velocity. | ||
| − | [[Image:dufresne.epl.2001-fig1.png|thumb|left|400px|Fig 1: "(a) Measured probability distribution for displacements along the direction of flow at | + | [[Image:dufresne.epl.2001-fig1.png|thumb|left|400px|Fig 1: "(a) Measured probability distribution for displacements along the direction of flow at \tau = |
| − | 1/60 s and 4/60 s for z = 4 μm. The solid curves are fits to eq. (3) for the width and displacement of the distribution. (b) Drift of the distributions’ centers along and perpendicular to the direction of the imposed flow. (c) Evolution of the mean-square widths of P ( | + | 1/60 s and 4/60 s for z = 4 μm. The solid curves are fits to eq. (3) for the width and displacement of the distribution. (b) Drift of the distributions’ centers along and perpendicular to the direction of the imposed flow. (c) Evolution of the mean-square widths of P(r_i, \tau|z), fit to eq. (1) for D_i(h)."]] |
Revision as of 00:44, 21 September 2010
Original Entry by Tom Dimiduk, AP225 Fall 2010
Brownian Dynamics of a Sphere Between Parallel Walls E. R. Dufresne, D. Altman and D. G. Grier
Soft matter Keywords
Brownian Motion, Surface
Summary
To the right is a diagram showing my best interpretation of the apparatus the authors used to make high resolution measurements of the brownian motion of a sphere confined along one dimension by two glass planes 8 microns apart. They positioned a 1 micron sphere in a precise position using an optical trap, then released it to study motion. They imaged with a video microscope at 60 Hz and used particle centroiding to obtain a resolution of 20 nm in x and y. They obtained z information by repeating the experiment releasing the particle from the same location with the microscope focused at differing heights. They measure distance from the wall by running a steady poiseuille flow and observing its effect on the particle velocity.
