Abstract: The present invention relates to a channel structure for a bioreactor, biochemical reactor, chemical reactor or a reformer comprising a plurality of individual layers stacked on one another and having a respective plurality of openings which pass completely through the respective individual layer and which are characterized in that at least two directly adjacent individual layers each have at least one layer section whose openings are arranged in the form of a pattern respectively regular in two dimensions and in that at least two of the layer sections provided with such a pattern in this manner of directly adjacent individual layers overlap at least in part, wherein the openings of the two at least partly overlapping layer sections are rotated and/or offset with respect to one another in the overlap region.