(600i) Non-Antiperiodic Electrophoresis of Colloidal Particles (NANEP)

We provide the first direct experimental observation and computational prediction of non-antiperiodic electrophoresis (NANEP), by imposing a sinusoidal non-antiperiodic voltage to charged colloidal particles in a microfluidic device. We attain net motion of micron-sized polystyrene particles driven by nonlinear-electrophoresis, demonstrating that a net drift can be obtained with the application of AC signals without the need of a DC bias. AC voltages with amplitude of 150 and 500 V were applied and particle position was tracked and compared with the predictions from simulations of the full nonlinear electrokinetic equations, obtaining good agreements in both the amplitude of the particle position oscillation and its net drift. Further experiments consisted of ranging the amplitude of the voltage signal to build a net-drift speed profile as a function of the electric field amplitude. Furthermore, simulations predict fore-aft asymmetry in the both the velocity profile and disturbance electric field in the vicinity of the particle, when averaged over one period of the signal, consistent with a non-zero net drift.