A micro-fluidic device for fractionating a sample of analytes according to their isoelectric points, the device comprising: a micro-fluidic chamber comprising one or more walls and a separation chamber zone contained within the one or more walls; an inlet port situated at a first end of the micro-fluidic chamber for introducing a sample of analytes into the separation chamber zone; a plurality of outlet ports situated at a second end of the micro-fluidic chamber substantially opposite the first end, the plurality of outlet ports extending across a width that is equal to at least part of a width of the separation chamber zone; a plurality of channels each leading from a different widthwise position in the separation chamber zone to one of the plurality of outlet ports; and one or more flow path deflector elements (10, 11) situated proximate the inlet port and situated between the inlet port and the plurality of outlet ports, the one or more flow path deflector elements (10, 11) being situated in one or more positions preceding the separation chamber zone; wherein the separation chamber zone does not include any flow path deflector elements (10, 11) and is formed of an open area in which analytes of the sample can migrate and separate according to isoelectric points under the presence of a generated electric field; wherein the one or more flow path deflector elements (10, 11) are positioned in such a way as to prevent substantial lateral intermixing of a plurality of fractionated analyte groups as the plurality of fractionated analyte groups flows from one or more positions in the separation chamber zone to the plurality of channels; and wherein at least one of the one or more flow path deflector elements (10, 11) blocks a shortest path between the inlet port and at least one of the plurality of outlet ports. a micro-fluidic chamber comprising one or more walls and a separation chamber zone contained within the one or more walls; an inlet port situated at a first end of the micro-fluidic chamber for introducing a sample of analytes into the separation chamber zone; a plurality of outlet ports situated at a second end of the micro-fluidic chamber substantially opposite the first end, the plurality of outlet ports extending across a width that is equal to at least part of a width of the separation chamber zone; a plurality of channels each leading from a different widthwise position in the separation chamber zone to one of the plurality of outlet ports; and one or more flow path deflector elements (10, 11) situated proximate the inlet port and situated between the inlet port and the plurality of outlet ports, the one or more flow path deflector elements (10, 11) being situated in one or more positions preceding the separation chamber zone; wherein the separation chamber zone does not include any flow path deflector elements (10, 11) and is formed of an open area in which analytes of the sample can migrate and separate according to isoelectric points under the presence of a generated electric field; wherein the one or more flow path deflector elements (10, 11) are positioned in such a way as to prevent substantial lateral intermixing of a plurality of fractionated analyte groups as the plurality of fractionated analyte groups flows from one or more positions in the separation chamber zone to the plurality of channels; and wherein at least one of the one or more flow path deflector elements (10, 11) blocks a shortest path between the inlet port and at least one of the plurality of outlet ports.