Precision micromilling is currently widely used for the fabrication of injection mold inserts for the mass production of microfluidic devices. However, for complex devices with micrometer-scale and high density of structures, micromilling results in high production times and costs for production runs of hundreds or thousands of units. Femtosecond laser (fs-laser) technology has emerged as a promising solution for high-precision micromachining. This study analyzes the potential of fs-laser micromachining for the fabrication of injection mold inserts for the large-scale production of thermoplastic microfluidic devices. For the evaluation of technology, a reference design was defined. The parameters of the fs-laser process were optimized to achieve high resolution of the structures and optimal surface quality, aiming to minimize production times and costs while ensuring the quality of the final part. The microstructures were replicated in two different grades of COC (Cyclic Olefin Copolymer) by injection molding. The dimensional tolerance of the structures and the surface finish achieved both in the insert and the polymer parts were characterized by scanning electron microscopy (SEM) and confocal microscopy. The surface quality of the final parts and its suitability for microfluidic fabrication were also assessed performing chemical bonding tests. The fs-laser machining process has shown great potential for the mass production of microfluidic devices. The developed process has enabled for a reduction of up to 90% in the fabrication times of the insert compared to micromilling. The parts exhibited very smooth surfaces, with roughness values (Sa) of 64.6 nm for the metallic insert and 71.8 nm and 72.9 nm for the COC E-140 and 8007S-04 replicas, respectively. The dimensional tolerance and the surface quality need to be improved to be competitive with the finishes achieved with precision micromilling. Nonetheless, there is still room for improvement considering the significant reduction in the production times through new laser processing strategies.

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.