Authors: Y. Shen, S. Tada, Z. Qiu
Affilation: The City College of the City University of New York and New York Center for Biomedical Engineering, United States
Pages: 537 - 540
Keywords: memories of polarization interactions, particle transport, particle instability
On the Nanotech 2008 in Boston, we reported our experimental observations of the particle instability and island-like structures in the suspension of poly alpha olefin particles and corn oil when the suspension was exposed to an AC gradient electric field generated by a spatially periodical electrode array. In dilute suspensions, the particle instability is well developed to form island-like structures; while in concentrated suspensions, the particle instability is suppressed by the DEP force and particles only form uniform particle stripe. Here, we will present our understandings of why or how particles form island-like structures via molecular dynamics simulations. The simulations have quantitatively reproduced our experimental findings of formation of island-like and present clear physical pictures about our experimental findings. Dipole–dipole interactions induce particle clustering first ; even during DEP induced transport of particles, memories of the polarization interactions are kept. The memories drive particle instability. In physics, we discovered the memories of polarization interactions that are kept even when particles are transported by the DEP force. In application, our findings will lead to useful techniques for separation of cells in different biological states.