Abstract: The present invention is generally directed to improved microfluidic devices, systems and methods of using same, which incorporate channel profiles that impart significant benefits over previously described systems. In particular, the presently described devices and systems employ channels having, at least in part, depths that are varied over those which have been previously described. These varied channel depths provide numerous beneficial and unexpected results.

Abstract: In a microfluidic system using electrokinetic forces, the present invention uses electrical current or electrical parameters, other than voltage, to control the movement of fluids through the channels of the system. Time-multiplexed power supplies also provide further control over fluid movement by varying the voltage on an electrode connected to a fluid reservoir of the microfluidic system, by varying the duty cycle during which the voltage is applied to the electrode, or by a combination of both. A time-multiplexed power supply can also be connected to more than one electrode for a savings in cost.

Abstract: The present invention provides for techniques for transporting materials using electrokinetic forces through the channels of a microfluidic system. The materials are transported in slug regions of high ionic concentration, next to buffer material regions of high ionic concentration, which are separated by buffer material regions of low ionic concentration. Such arrangements allow the materials to remain localized for the transport transit time to avoid mixing of the materials. Using these techniques, an electropipettor which is compatible with the microfluidic system is created so that materials can be easily introduced into the microfluidic system. The present invention also compensates for electrophoretic bias as materials are transported through the channels of the microfluidic system by splitting a channel into portions with positive and negative surface charges and a third electrode between the two portions, or by diffusion of the electrophoresing materials after transport along a channel.