Design of Particle Trapping Using an Analytical Solution of Electroosmotic Microvortices in a Semicircular Conduit

• Main Authors: Kuan-HongChen, 陳冠宏
• Other Authors: Shyh-Hong Hwang
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/z69md6

碩士 === 國立成功大學 === 化學工程學系 === 104 === This thesis first investigates microfluidic electroosmotic flow set up by electrokinetic slip velocities over charged strips in a semi-infinite domain. A two-dimensional closed-form solution is derived for electroosmotic flow induced by a simple polynomial slip-velocity distribution over a surface. Using the cubic spline interpolation and superposition principle, an arbitrary slip-velocity distribution can be well approximated to provide a general analytical solution for electroosmotic flow in a semi-infinite plane. On the other hand, electrokinetic slip velocities would induce electroosmotic microvortices in a semicircular domain. The thesis combines an analytical solution for microvortices from the literature and the aforementioned planar solution to develop a complete mathematical model for microvortices in a semicircular area. This model not only satisfies practical operating conditions but also possesses accuracy and fast convergence in computation. The thesis then addresses the problem of particle trapping at a specified point in a semicircular area using microvortices and short-range force from the bottom. The aim is to design the best microvortex structure and arrange the corresponding slip velocities. To this end, a symmetric microvortex structure is first analyzed to divide the semicircular area into several easy-to-trap and difficult-to-trap regions according to the duration of particle trapping time. Various arrangement strategies for slip velocities are then proposed to meet the requirements given by different initial distributions of particles. Simulation studies based on random particle distributions demonstrate that the microvortex structures caused by the proposed strategies can capture particles more efficiently at a stagnation point on the bottom. Compared to the symmetric microvortex structure, the trapping time can be reduced by 30%.