Fraunhofer FEP: Coating Processes for Filter Membranes
Fraunhofer FEP has developed a coating process for the production of ultrathin carbon nanomembranes. The technology enables efficient water filtration and has been integrated into a continuous roll-to-roll process for the first time.
The Fraunhofer Institute for Electron Beam and Plasma Technology FEP, in collaboration with the startup CNM Technologies GmbH, has developed a novel filtration technology as part of the European research project Convert2Green. At the heart of the technology is a highly cross-linked polymer layer made of carbon nanomembranes (CNM) that is only a few nanometers thick. The unique structure of this membrane allows water molecules to pass through while almost completely retaining dissolved ions, organic substances, and other molecules. On a laboratory scale, the technology has been shown to provide at least five times better retention of sodium chloride compared to conventional osmosis membranes, while maintaining the same water flow rate. CNM composite membranes are suitable, among other things, for the gentle concentration of aqueous solutions in the food industry and for the production of ultrapure water via low-pressure reverse osmosis.
Electron-beam crosslinking and roll-to-roll coating
A major milestone was the first-ever implementation of all manufacturing steps—from the deposition of a monolayer to its cross-linking via electron beam—in a continuous roll-to-roll process. With this achievement, Fraunhofer FEP succeeded in transferring the production of these novel membranes from the laboratory scale to an industrially relevant process environment. This represents a decisive step forward on the path to the economic scaling of the coating technology. In a further development step, the researchers optimized the process by integrating additional metal layers. This enabled the production of ultrathin metal films with a thickness of just a few tens of nanometers, opening up new application possibilities, particularly in miniaturized optics and sensor technology. The Convert2Green project, which was completed in the spring of 2026, was funded under Horizon Europe and involved 18 partners from nine countries. The technology will be presented at the Pro Flex 2027 conference, taking place May 25–26, 2027, in Dresden.
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