Filter for chemical reactors

A chemical reactor implemented on a substrate, the chemical reactor comprising:

• an inlet for receiving a fluid and/or a gas, wherein the inlet has a first depth dhigh and has been adjusted to accommodate a capillary,
• a filter element for reducing or preventing that materials cause a blockage in the fluid and/or gas supplied in a part of the chemical reactor located further away, and
• a part located further away for transporting and/or processing the fluid and/or the gas, wherein the part located further away has a depth dlow smaller than depth dhigh of the inlet,
• wherein
• the filter element comprises a first duct part and a second duct part, wherein
• the first duct part is positioned closer up against the inlet than the second duct part,
• the first duct part has a greater depth than a depth of the second duct part,
• the first duct part has a diverging width so that the first duct part has a widening of the width in a downstream direction from the duct inlet towards the part located further away and the first duct part is free from pillar structures, and
• the second duct part is filled with filter pillars.