Microstructured devices are widely used for manufacturing products that benefit from process intensification, with pharmaceutical products or specialties of the chemical industry being prime examples. These devices are ideally used for processing pure fluids. Where particulate or non-pure flows are involved, processes are treated with utmost caution since related fouling and blocking issues present the greatest barrier to operating microstructured devices effectively. Micro process engineering is a relatively new research field and there is limited understanding of fouling in these dimensions and its underlying processes and phenomena. A comprehensive review on fouling in microstructured devices would be helpful in this regard, but is currently lacking. This paper attempts to review recent developments of fouling in micro dimensions for all fouling categories (crystallization, particulate, chemical reaction, corrosion and biological growth fouling) and the sequential events involved (initiation, transport, attachment, removal and aging). Compared to fouling in macro dimensions, an additional sixth category is suggested: clogging by gas bubbles. Most of the reviewed papers present very specific fouling investigations making it difficult to derive general rules and parameter dependencies, and comparative or critical considerations of the studies were difficult. We therefore used a statistical approach to evaluate the research in the field of fouling in microchannels.

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A method is proposed for the transfer from a batch production process for writing ink to continuous manufacturing by employing micro-process engineering. Special challenges arise from handling reactant streams with solids, high viscosities and flow ratios, which differ significantly from unity. Four different types of micromixers are tested by optimizing mixing effectiveness versus operational robustness. For the best suited mixer, a 48 h continuous production run is performed producing ink within specification at all times. A significant reduction of the plant hold-up is achieved for the conti manufacturing plant in comparison with the batch process. Initial cleaning experiments suggest that the specific wastewater production may be reduced by a factor of 1000 through micro-conti manufacturing.

Traditional process development consists of four main phases resulting in time‐consuming and cost‐intensive launches for new products and processes. By employing microprocess technology, transferring batch to continuous processes or setting up a continuous process for low to medium production capacities from scratch becomes technically feasible. Since volumetric flow rates on lab‐scale are often similar to production rates, the scale‐up factor is low. Thus, individual development phases can be omitted reducing the time‐to‐market for new products and/or processes. Based on two case studies, the development phase of micro‐conti processes is described and conclusions are drawn regarding the 50 % idea as laid down in the Tutzing theses.