  Mixing is one of the basic functions which automated lab-on-chips require for
the effective management of liquid samples. In this paper we report on the
working principle, design, fabrication and experimental characterization of a
soft-lithographed micromixer for microfluidic applications. The device
effectively mixes two liquids by means of chaotic advection obtained as an
implementation of a Linked Twisted Map (LTM). In this sense it is chaotic. The
liquids are electrokinetically displaced by generating rolls through AC
electroosmosis on co-planar electrodes. The device performance has been tested
on dyed DI-water for several voltages, frequencies and flow-rates, displaying
good mixing properties in the range of $10 \div 100$kHz, at low peak-to-peak
voltages ($\sim15 \div 20$ volts). Low voltage supply, small dimensions and
possibility of fabrication via standard lithographic techniques make the device
highly integrable in lab-on-a-chip platforms.
