Patent ID: 7691250

Claim:
A membrane-mediated electropolishing process comprising: a. providing a cathode half-cell comprising: 1. a fully or partially enclosed volume, cavity or vessel; 2. an electrolyte solution or gel that partially or substantially fills the enclosed volume, cavity or vessel; 3. an electrode in contact with the electrolyte solution or gel; 4. a means for electrically connecting the electrode to a DC power source; and 5. a charge-selective ion-conducting membrane that seals one surface of the enclosed volume, cavity or vessel in such a way that the internal surface of said membrane contacts the electrolyte solution or gel and the external surface is accessible to contact the metal work piece and a low-conductivity solvent or solution, and wherein the membrane is topographically patterned with lands of width W L and channels of depth D C situated on the external surface of the membrane, and the channels extend to the edges of the contour area; b. substantially covering a surface of a metal work piece with a low-conductivity solvent or solution; c. providing a source of DC electrical power whose positive terminal is connected to the metal work piece and whose negative terminal is connected to the electrode in the half-cell; and d. contacting the metal work piece with at least a portion of the external surface of the membrane.