题 目：声场和磁场下微颗粒的操控（Manipulation of micro-particles with acoustic and magnetic fields）
报告人：王成 博士（密苏里科技大学 ）
时 间：2017年6月21日（周三）9：00
地 点：延长校区应用数学和力学所东会议室
摘 要：Manipulation of micron-sized particles in microfluidic environment is important for
lab-on-a-chip systems, particularly those concerning biology and biomedical applications. At the micrometer length scale, external force fields, e.g., acoustic, electrical, magnetic, and optical forces, offer effective means to actuate and control micro-hydrodynamic flows as well as particle motions. In this presentation, two simple and powerful methods of micro-particle manipulation will be discussed. The first method utilizes acoustic streaming flows arising from microbubbles. Driven by an acoustic pressure field at ultrasound frequencies, microbubbles establish steady vortical flows through the Reynolds stresses in the boundary layer. We demonstrate sorting, enriching and focusing of micro-particles with this unique type of flow. The second method demonstrates a novel technique to separate non-spherical micro-particles by combining an external uniform magnetic field with a pressure-driven flow in a icrochannel. Our experimental measurements show that non-spherical microparticles migrate laterally due to combined effects of asymmetric rotational velocities and particle-wall hydrodynamic interactions.
