Patent ID: 7731827

Claim:
A method for capturing charged molecules of interest traveling in an electrolyte flowing stream through an electrically non-conductive channel comprising at least one anode and at least one cathode individually separated from said channel but in electrical contact with said flow stream by a conductive semi-permeable membrane, said method comprising the steps of: permitting via said membrane the selective passage of certain charged ions or molecules and blockade of others, which interferes with the normal circulation of ions towards one or more electrodes, thereby accumulating inside the channel ions that are not allowed to pass through the semi-permeable membrane, but not accumulating those which are attracted by the respective counterpart electrode, and by this means generating at least two zones with different ionic strength, conductivity and local electric field strength; whereby the zone having a lower electric field strength is situated upstream from the one having a higher electric field strength; applying a hydrodynamic force to the channel, said hydrodynamic force being greater than and opposed to the electrical force generated on the charged molecules of interest situated at the zone with lower local electric field strength; therefore pushing the charged molecules of interest downstream towards the zone with higher electric field strength, and lower than and in opposition to the electrical force generated in the zone with higher electric field strength, resulting in that the charged molecules of interest are pushed back up-stream towards the zone with lower electric field strength; where the process is repeated, thereby stacking the ions between the zones with different electric field strengths; the zone with higher electric field strength is situated upstream from the one with lower electric field strength; wherein charged molecules, attracted by the upstream electrode, are pulled with an electrical force greater than the hydrodynamic force of the flow stream, and not allowed to pass through the ion selective membrane, are retained on the surface of the membrane.