Nano-Structuring of Polymer Surfaces by Multi-Beam Laser Interference for Application in Micro-Fluidics

The interference of three coherent laser beams of a HeCd-laser with a wavelength of 325 nm was used to create a periodic intensity distribution into the photo-resist AZ4562. The beam configuration for the laser beam interference was carefully chosen, so that well defined patterns of two-dimensional periodicity were generated in the photo-resist. Moulding tools were fabricated from the generated nano-structures via electroforming processes, allowing for a fast replication of the nano-structured surfaces via hot embossing. Hot embossed polymers were used to increase the effective surface of micro-fluidic devices like e.g. Polymerase-Chain-Reaction(PCR)-chips. The Nano-structured surfaces were characterized concerning their contact angles when wetted with de-ionized water. It was found that the nano-structures influenced the wetting behaviour of micro-fluidic chip surfaces clearly, especially Polypropylene (PP) surfaces showed a superhydrophobic behaviour.