Three-dimensional micro-channels in polymers: One-step fabrication

We report on the femtosecond laser fabrication of micro-channels of sub-micrometer cross section recorded in polymethylmethacrylate (PMMA) films in a single processing step. Both axial lengths of an elliptical cross section smaller than 0.4 μm were achieved for a fabrication irradiance close to the dielectric breakdown of PMMA. Femtosecond pulsed irradiation was scanned along the three-dimensional (3D) patterns inside the film. Channels have a self-formed densified cladding and can be 3D stacked into any pre-designed pattern and can extend over a mm length. These features are prospective for micro-total analysis system (μ-TAS) chip fabrication, micro- or nano-fluidic studies, and photonic applications such as photonic crystals.