Molding topologically-complex 3D polymer microstructures from femtosecond laser machined glass

The fabrication of complex, three-dimensional microscale shapes that can be replicated over large surfaces is an ongoing challenge, albeit one with a wide range of possible applications such as engineered surfaces with tuned wetting properties, scaffolds for cell studies, or surfaces with tailored optical properties. In this work, we use a two-step femtosecond laser direct-write technique and wet-etching process to fabricate monolithic glass micromolds with complex three-dimensional surface topologies, and demonstrate the replication of these structures in a soft polymer (polydimethylsiloxane, PDMS). To estimate the forces experienced during the demolding for one representative structure, we use a combination of two models – a simple linear elastic model and a numerical hyperelastic model. These models are used to support the high experimental success rates of the demolding process observed, despite the high strain induced in the material during demolding. Since the process used is scalable, this work opens new avenues for low-cost fabrication of surfaces having complex microscale patterns with three-dimensional geometries.