Dual-asymmetry electrokinetic flow focusing for pre-concentration and analysis of catecholamines in CE electrochemical nanochannels.

In this research, a technique incorporating dual-asymmetry electrokinetic flow (DAEKF) was applied to a nanoCE electrochemical device for the pre-concentration and detection of catecholamines. The DAEKF was constructed by first generating a zeta-potential difference between the top and bottom walls, which had been pre-treated with O2 and H2O surface plasma, respectively, yielding a 2-D gradient shear flow across the channel depth. The shear flow was then exposed to a varying zeta-potential along the downstream direction by control of the field-effect in order to cause downward rotational flow in the channel.