Patent ID: 7243670

Claim:
A method to transport a substance within a microfluidic system having an operational channel in which the substance is moved by a driving force in a direction of the operational channel, wherein the method comprises: applying the driving force; measuring a variable assigned to the substance and derivable in an area of the substance; and regulating the driving force based on the measured variable, wherein the microfluidic system is configured as an open network of mutually fluid-connected channels that feed into a common channel chamber, wherein at least one of the channels functions as a measurement channel, wherein each of the ends of the channels away from the common chamber is in contact with an electrode that is used to exert an electrical field on the fluid, wherein the electrodes are supplied with an electrical force, wherein a first electrode is assigned to a first channel and a second electrode is assigned to a second channel, and wherein said method further comprises: regulating an electrical current (I 2 ) to a target value at the second electrode, wherein the second electrode functions as a measurement sensor; measuring an electrical voltage (U 2 ) at the second electrode, wherein a voltage (U 1 ) is applied to the first electrode; and regulating the electrical voltage (U 1 ) at the first electrode in such a manner that a difference between U 1 and U 2 achieves a pre-determined value.