An integral filter is fabricated by patterning a layer of etch resistant material on one side of a (100) silicon wafer to produce an array of equally spaced, uniformly sized posts or shapes and doping the exposed surface of the wafer by boron ion implant. The dopant is diffused into the wafer while the array of posts of etch resistant material masks the diffusion under them. The size of the posts or shapes determines the undoped areas of the wafer and, thus, the mesh size of the eventually produced integral filter. The wafer is recoated with a layer of etch resistant material and the other side, which was not doped, is patterned to form a plurality of sets of elongated channel vias and reservoir vias, one reservoir via for each set of channel vias. The wafer is orientation dependently etched for a predetermined time period to produce the sets of channel grooves and reservoir recesses, the recesses having a depth of about 75-85% of the wafer thickness, followed by etching of the wafer in an EDP etchant to finish etching the reservoirs through the wafer. The doped silicon area is not etched, so that an integral filter is produced having an arbitrary pore size determined by the size of the posts or shapes patterned initially prior to the diffused doping step.