Screen filter

Abstract: A multi-purpose screen filter structure in silicon has been fabricated and characterized. The fabrication of the filter structure is based on a two-step self-aligning process using lateral boron doping, anisotropic silicon etching and silicon dioxide undercut etching. Filters for filtration of particles down to 50 nm have been fabricated. The flow resistance for gases and liquids has been measured. The fluid passes between two electrically conducting membranes, so other applications such as fluid identification and concentration measurements are possible. A preliminary fluid identification experiment is presented.

Abstract: A filtration systems for fluids, particularly biological fluids. The filtration system includes a filter containing compartment connected at one end to a storage vessel and at the other end to a diaphragm pump. The filter comprises a hollow fiber module or a screen filter. The vessel serves as a storage container for a process stream to be filtered. The diaphragm pump provides the means for generating rapid, alternating, low shear tangential flow between the vessel and pump and through the hollow fibers or screen filter. The system allows easy removal of wastes from the fluid and the addition of fresh fluid to replenish the filtered fluid.

Abstract: The improved carpet cleaning machine, intended for use with "dry" carpet cleaning systems using dampened granules or particles, can be used in either of two modes. One involves carpet "brushing" for dirt removal by urging particles into the carpet and along the fibers. The other involves later vacuuming for particle removal. To facilitate the latter, one embodiment of the machine has first and second particle-removing media such as a concentrically-mounted cyclone separator and conical screen filter, respectively. The separator has air flowing through it downwardly along a vortical path and then upward, such air flow often carrying along a few particles. Such high-velocity particles impinge on the outer surface of the screen filter and many particles adhering to such filter are dislodged. The filter is said to thereby be "purged" or cleaned. There may also be a third medium and even a fourth medium to remove very fine particles before the air is expelled back into the room. Other embodiments use an automotive, resilient foam or flat-element filter medium in place of or in addition to the conical screen filter.