(419i) Morphological Effects On the Electrostatic Potential In a Divergent and Convergent Channel for Microfluidic Applications

A number of researchers have proposed combining electroosmotic flow (EOF) and pressure-driven flow as a means of controlling the motion and separation of bioparticles in diverging- converging microchannels¹. In order to get better understanding of role of electrostatic potential on fluid motion, analytical study of the electrostatic potential in divergent and convergent channels has been conducted in this study. Distribution of electrostatic potential is given by the solution of 2D Poisson-Boltzmann Equation (PBE) with both long channel and Debye –Huckel approximations. As a product of the investigation, one can assess the behavior of the electrostatic potential inside of a convergent-divergent section. Three key parameters have been identified to describe the electrostatic potential behavior: the angle (∝) of the convergent (or divergent) section (related to the walls of the channels) that handles the “magnitude” of the deviation with respect to a straight channel; the ratio of the wall potentials, R, which handles the symmetrical/non-symmetrical aspects of the electrostatic potential, and the ratio of the width to the length (γ) that controls the “shape” of the channel section. Results of this study will be shown by using a series of portraits that capture the key behaviors of the electrostatic potential with respect to the three parameters described above.

1-V. Gnanaraj, V. Mohan, B. Vellaikannan, “ Numerical Investigation of Electroosmotic Flow in Convergent Divergent Micronozzle”, In proceeding of the COMSOL Conference, Bangalore(2009).