Hybrid chemical etching of femtosecond irradiated 3D structures in fused silica glass

We report on the fabrication of 3D micro-structures in fused silica glass using chemical etching along femtosecond laser irradiated zones. In particular, we exploited a novel approach combining two different etching agents in successive steps: the hydrofluoric acid, which provides fast volume removal, and potassium hydroxide, which exhibits high selectivity. We demonstrated that this hybrid approach enables a more easy prototyping and fabrication of complex geometries for microfluidic devices.