Abstract: A separating device for use in separating electrically charged components, e.g., by electrophoresis, comprises a channel branched at a branch point to provide a main feed channel (105) connected to at least two subsidiary channels (110, 115). In use, different components (120, 125, 130) show differential migration along the feed channel (105) so they can be separated into different subsidiary channels (110, 115) at the branch point. To support this separation, the separating device is provided with switchable voltage control means for controlling local voltages in a region of the branch point to provide potential differences of opposing polarity along the respective subsidiary channels (110, 115) such that a component to be separated (125) can be caused to migrate from the feed channel into a different subsidiary channel (115) from one or more other components.