Solid state fluid transport and sensing based on printed and embedded cellulose-polymer composites: An alternative pathway to paper-based microfluidic devices

Here we present an alternative technological approach to paper-based microfluidics that, to the best of our knowledge, has not been reported so far. Instead of defining fluid conducting paths by cutting fluidic structures, or by printing hydrophobic substances on paper, we prepare cellulose/polymer composites that can be printed additively on, in principle, arbitrarily shaped substrates and surfaces. In this way, with respect to geometry and properties, well defined fluid conducting structures based on cellulose can be realized, that can additionally be fully embedded in an organic surface coating. Moreover, the composite can, prior to the printing step, be doped with a functional component, which facilitates the realization of printed analytical devices using just a single base material and process technology. In this sense, the proposed technology can be seen as an alternative pathway to paper-based microfluidics, that may be attractive for specific niche-applications such as, for example, bio-chemical assays embedded in the surface of everyday necessities or commodities. Especially lateral flow immunoassays, pandemic-driven needed in large quantities, may embody a future application field of the presented technology.