Physics Division, Oak Ridge National Laboratory, PO Box 2008, Bldg. 6010, Oak Ridge, TN 37831, USA.
Small. 2012 Mar 26;8(6):907-12. doi: 10.1002/smll.201101739. Epub 2012 Jan 23.
A charged microparticle can be trapped in an aqueous environment by forming a narrow virtual pore--a cylindrical space region in which the particle motion in the radial direction is limited by forces emerging from dynamical interactions of the particle charge and dipole moment with an external radiofrequency quadrupole electric field. If the particle satisfies the trap stability criteria, its mean motion is reduced exponentially with time due to the viscosity of the aqueous environment; thereafter the long-time motion of particle is subject only to random, Brownian fluctuations, whose magnitude, influenced by the electrophoretic and dielectrophoretic effects and added to the particle size, determines the radius of the virtual pore, which is demonstrated by comparison of computer simulations and experiment. The measured size of the virtual nanopore could be utilized to estimate the charge of a trapped micro-object.
带电荷的微粒可以通过形成狭窄的虚拟孔（即微粒在径向方向上的运动受到微粒电荷和偶极矩与外加射频四极电场之间的动态相互作用产生的力限制的圆柱空间区域）被限制在水相环境中。如果微粒满足陷阱稳定性标准，则由于水相环境的粘性，其平均运动随时间呈指数衰减；此后，微粒的长时间运动仅受随机布朗波动的影响，布朗波动的大小受电泳和介电泳效应的影响，并加上微粒的尺寸，决定了虚拟孔的半径，这通过计算机模拟和实验的比较得到了证明。虚拟纳米孔的测量尺寸可用于估计捕获微物体的电荷量。
