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We present a metamaterial consisting of a two-dimensional, asymmetric lattice of crossed nanochannels in fused silica, with channel diameters of 80 nm to 140 nm. When DNA is introduced, it is stretched and linearized. We show that the asymmetry in channel dimensions gives rise to a preferred direction for DNA orientation and a preferred direction for transport under dc electrophoresis. Interestingly, the preferred axis of orientation and transport can be switched by 90 degrees through application of an ac voltage. We explain the results in terms of an energy landscape for polyelectrolytes that consists of entropic and dielectrophoretic contributions and whose strength and sign can be tuned by changing the ac field strength.

We report an experimental investigation of the magnitude of length and density fluctuations in DNA that has been stretched in nanofluidic channels. We find that the experimental data can be described using a one-dimensional overdamped oscillator chain with nonzero equilibrium spring length and that a chain of discrete oscillators yields a better description than a continuous chain. We speculate that the scale of these discrete oscillators coincides with the scale at which the finite extensibility of the polymer manifests itself. We discuss how the measurement process influences the apparent measured dynamic properties, and outline requirements for the recovery of true physical quantities. [ABSTRACT FROM AUTHOR]

In this article, the electrokinetic motion of a non-conductive particle immersed in an aqueous solution in a microchannel is studied; the particle is subjected to a lateral temperature gradient that is perpendicular to the direction of the applied electric field. Three-dimensional governing equations are solved numerically to simulate the motion of the particle. It is noticed that the particle undergoes lateral and rotational movements as well as a longitudinal motion. The lateral and rotational motions of the particle will be affected by a size of the particle, an applied external electric field and an initial magnitude of temperature gradient. The results show that the initial magnitude of the temperature gradient is the most significant factor. It was observed that by doubling the temperature difference, the particle travels 64 percent more in lateral direction. It also rotates 42 percent more while experiencing a doubled temperature difference. Another parameter that has been investigated is the magnitude of the electric field. By halving the magnitude of the applied electric field, the particle moves laterally 10 percent less for a constant longitudinal distance. Finally, it was discovered that the effect of size of the particle on its velocity is negligible. [ABSTRACT FROM AUTHOR]