Abstract: A fluidic device is disclosed for making electrophoresis of molecules. The device has channels of closed geometry and variable powers over time. Migration of molecules is contained within channel of closed geometry, whereby they can circulate again and again, thus separating the molecules at a wide migration distance. The device has an injection system which is a secondary channel which intersects the main channel. An arrangement of electrodes along this main channel connected to a variable voltage source with multiple outlets which regulates the value of the electric power in each electrode, and the frequency at which the same varies from one electrode to another. Thus it is achieved to generate a periodic arrangement of powers along the channel which set the flow of the sample optimizing the separation process. Electrodes can be added for the detection of molecules by measuring the changes in electric resistivity, current or voltage.