Wang Ping, Maheshwari Siddharth, Chang Hsueh-Chia
Center for Microfluidics and Medical Diagnostics, Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Phys Rev Lett. 2006 Jun 30;96(25):254502. doi: 10.1103/PhysRevLett.96.254502. Epub 2006 Jun 27.
New deformation or fission phenomena are reported for microdrops driven by an ac electric field at their resonant frequencies. The Maxwell forces that pull out the vertices from a drop can be enhanced when the ac frequency is comparable to both the drop resonant frequency and the inverse charge relaxation time of the diffuse layer. The selected polyhedra possess symmetries that ensure a global force balance of the Maxwell forces and a linear dimension consistent with a sphere whose nth harmonic (n is up to six in the observation) coincides with the applied ac frequency. At high voltages, the resonant focusing of charges by the vibration modes produces evenly distributed and transient Taylor cones that can eject charged nanodrops.
报告了在交流电场驱动下，微滴在其共振频率时出现的新的变形或裂变现象。当交流频率与液滴共振频率以及扩散层的反电荷弛豫时间相当时，从液滴中拉出顶点的麦克斯韦力会增强。所选择的多面体具有对称性，可确保麦克斯韦力的整体力平衡以及与球体一致的线性尺寸，该球体的第n阶谐波（在观察中n高达六）与所施加的交流频率一致。在高电压下，通过振动模式对电荷的共振聚焦会产生均匀分布且瞬态的泰勒锥，这些泰勒锥可以喷射带电的纳米液滴。
