Measurement of the Velocity Profile Near the Wall in Bio-Fluid Flow Using Evanescent Light Source Available to Purchase

For the investigation of near surface phenomena, a novel method, which is to measure velocity profile in the direction of depth, are suggested. By changing the angle of induce light, illuminated penetration depth is changed. The velocities of fluorescent tracers are successfully measured using PTV technique. The fluid including bio-molecules is employed for velocity measurement. The velocity profile of bio-fluid is measured by eliminating the influence of the Brownian motion of tracers. The velocity profile of the flow agrees well with the plane Poiseruille flow equation except for the results at large distance from the wall. It is assumed that the difference in the velocity at the large distance results from the inhomogeneous concentration profile due to surface potential. In our knowledge, the method suggested in this study is the first one in terms of measuring flow velocity profile in direction of depth near wall surface.