Abstract: In an electroforming method for making metal products having a pattern of openings separated by dykes using a mandrel in an electroplating bath, metal from the bath is deposited on at least two electrically mutually insulated regions. Said regions comprise at least one main pattern for product dykes to be formed, which main pattern is electrically insulated from at least one ancillary pattern for a reinforcement to be formed. In the method according to the invention, first the ancillary pattern is connected to a current source in order to form reinforcement thereon and in order to effect an electrical connection between the ancillary pattern and the main pattern by means of the growing metal. During the continuation of the method, reinforcement is thickened and the product dykes are formed. A strong product having different thicknesses is therefore obtained in one step. A mandrel suitable for use in the method is also described.

Abstract: The inorganic membrane consists of a macroporous inorganic support and an inorganic membrane layer. The membrane layer is formed through depositing an inorganic layer by "Chemical Vapour Deposition" or "sputtering" on the macroporous support, onto this inorganic layer a photo-lacquer layer is formed, this photo-lacquer layer being exposed to a regular mask pattern with the use of a suitable source, this lacquer layer being developed, and in the inorganic layer the mask pattern is etched by a suitable etchant, thus forming the membrane layer. The pattern of the membrane layer may be given any particular design, practically with a repetition rate in the range 0.1-10 .mu.m. It is thus conceivable to separate not only particles according to their size, but also to their shape. The membrane layer can be deposited very thinly in comparison to the dimension of the pore size, enabling a large flux, a reduced clogging and a minimal damage to particles or cells.