NOVELTY - Solid oxide fuel cell structure obtainable by selective electrochemical processing, comprises an electrolyte membrane, and a metallic grid. The metallic grid is applied over the electrolyte membrane and serves as structural element to support the membrane and as current collector. The metallic grid has gridlines that are higher than the membrane thickness and has height to width ratio of larger than 0.5.    USE - As a gas sensor and for generate voltage (claimed) and current.    ADVANTAGE - The metallic grid structure with a mesh size that is usually 10 - 1000 times smaller than the substrate opening supports the membrane to avoid cracking caused by excessive stresses and buckling. The membrane thinness is chosen to allow compatibility with thin film and micromachining technology. Because of grid's morphology and its aspect ratio, more space is left for the porous anode material, which is easier to access. The metallic grid is relatively thick and open, thus allowing better opportunities for 3-phase contact leading to better performance. The membrane (electrolyte in our case) is not perforated during fabrication of the supporting structure. The supporting structure is on one side only (anode) and can be made with a metallic material and with high aspect ratio. The fabrication of solid oxide fuel cell is less complicated and less expensive, as it uses electrochemical deposition of typically nickel. The metal grid is used at the same time to work as current collector, thus supporting the functionality of thin porous electrodes, as typically used on the anode side. The fuel cell has a thin metallic network structure on the side opposed to the supporting metallic grid to collect the current on this side and connect to a contact pad on the same side as the other one. The side with the contacts is preferentially the anode side, thus in reducing atmosphere, in order to avoid oxidation of contact metals. The supporting grid provides high aspect ratio, thus providing high efficiency of the cell.    DETAILED DESCRIPTION - Solid oxide fuel cell structure obtainable by selective electrochemical processing, comprises an electrolyte membrane, and a metallic grid. The electrolyte membrane is formed by a thin film having thickness of 50 nm - 10 microns, covering a supporting structure made of a bulk substrate, where the supporting structure has at least one opening that is 100 microns - 100 mm wide and covered by the electrolyte membrane. The metallic grid is applied over the electrolyte membrane and serves as structural element to support the membrane and as current collector. The metallic grid has gridlines that are higher than the membrane thickness and has height to width ratio of larger than 0.5. The metallic grid has a mesh size of 10 - 1000 times smaller than the width of opening. The metallic grid is applied on top of a patterned metallic sub-layer structure arranged for supplying fine distribution of current and increasing the density of electrolyte electrode boundaries exposed to fluid. The structure further comprises a porous anode film, and a porous cathode film. The metallic grid is molded in a polymer mold, in particular of photoresist.    INDEPENDENT CLAIMS are included for the following:    (1) producing the solid oxide fuel cell structure involving photolithographic patterning and electrochemical, physical and chemical vapour processing of successive layers on an etchable substrate, where the membrane and the metallic grid are applied to the substrate, and the substrate is etched to provide the opening; and    (2) an array of structures, which are fabricated on a common substrate and connected electrically to form array of solid oxide fuel cells.    DESCRIPTION OF DRAWING(S) - The figure shows a positive electrode-electrolyte-negative electrode of fuel cell structure with cathode collector grid.