Figure 2.

Effect of ratchet structure on the dielectrophoretic focusing of 5 µm diameter particles: (a) Comparison of the experimentally obtained and numerically predicted (top half of the left- and right-most images only) particle trajectories (traveling from left to right) at varying locations of the microchannels with symmetric (top row), asymmetric forward (middle row), and asymmetric backward (bottom row) ratchets, respectively; (b) Comparison of the experimentally measured (symbols with error bars) and numerically calculated (curves) particle focusing ratios, defined as the channel width, $W$, over the particle stream width, $W_p$ (see the highlighted dimensions in (a)), among the three ratchet structures.