Femtosecond‐Laser Mould Texturing Enables Tunable Biointerfaces in COC Microfluidics

Cyclic Olefin Copolymers (COCs) are increasingly used in microfluidic biomedical devices, although their chemically inert surfaces may hamper control of protein adsorption and cell–material interactions. Here, femtosecond laser texturing is applied to mould inserts to generate micro‐ and nano‐scale features that are subsequently replicated onto COC by injection moulding. Surface characterization confirms accurate texture transfer and reveals a direct correlation between replicated geometry and wetting behaviour. Protein adsorption assays show that different textures promote heterogeneous protein deposition, indicating that topographical cues regulate the early formation of the biointerface. Cell culture studies demonstrate that variations in topography and wettability across textures lead to texture‐dependent cell adhesion trends when compared to a conventional collagen‐coated reference, highlighting the role of mould‐encoded physicochemical cues. Because the textures are introduced at the mould level, the method is compatible with industrial, high‐throughput production of polymer‐based microfluidic devices. Overall, this work establishes a scalable strategy to engineer COC surfaces with customized wetting and biological properties using fs‐laser mould texturing combined with injection moulding, providing a robust route to integrate micro‐ and nano‐engineered functionalities without chemical treatments.