AC electrokinetic effects generated by a pair of electrodes (horizontal gold or black bars) located on the surface of a non-conductive substrate. a) A schematic representation of a particle undergoing pDEP (left) and nDEP (right)in a non-uniform electric field.b) The reported mechanism for AC-electroosmosis where the arrows indicate fluid flow driven down towards the electrode gap and out along the surface of the electrode due to the force of the tangential component of the electric field on the ions in solution. Adapted from Morgan & Green (2003). c) Circulation pattern of fluid near the electrode edge created by electrothermal effects where the arrows indicate the net force on a suspended particle with an rp of 200 nm. The colour intensity indicates the magnitude of the fluid velocity with an scale bar in log10m/s. The circulation zones appear to be similar to a microfluidic system subjected to AC electroosmotic flow