The present invention provides a method for the electrophoretic separation of particles, especially of macromolecules, comprising the steps of applying the particles to be separated on a substrate supported membrane, such that the particles are mobile across the surface of the substrate supported membrane; providing an electrical field such that electrical fields are formed along the surface across which the particles are mobile; and temporarily modifying the electrical field and/or adding a substrate supported membrane having a structured surface, wherein the direction and/or the strength of the electrical field are temporarily modified and/or wherein the substrate supported membrane is structured so that a force is acting on the particles that leads to a movement depending on the length of the particles. Moreover, a substrate is provided, in particular, for supporting a membrane during the performing of the inventive methods, that comprises an optically transparent material. Moreover, the invention provides a substrate supported membrane for carrying out the inventive methods including an inventive substrate as defined in the claims and a fluid lipid membrane. Moreover, the present invention provides a microchannel electrophoresis chamber having at least one channel with a bottom surface including an inventive substrate, and an electrode assembly.