Microchannels transport pressure-driven flows

As the usual parabolic velocity profile of pressure-driven Poiseuille flow leads to the flow rate scaling as R whereas the flat velocity profile obtained in pure electroosmotic flow gives rise to a flow rate that scales as R, it can be seen that it is more efficient to drive microchannel flows where R becomes very small using electrokinetic flows as opposed to pressure-driven flow. However, there are some design issues to be considered in electrokinetic bubble transport. 

Pressure driven flow, for which/ is zero in Eq. (la), tends to be the simplest transport mechanism to implement and is accomplished by applying a mechanical pressure difler-ence between an inlet and an outlet port. For the simplest case of pressure driven flow in a microchannel with low aspect ratio it can be shown that the average velocity in the channel is described by Eq. (2) below. 

---