Laser-assisted structuring of metal-polymer bilayers for protein patterning

The fabrication of biomedical microdevices requires patterning techniques that can print structures ranging from hundreds of microns to sub-micron sizes, on large areas, with a low cost of ownership, and using essentially any material, but with relatively relaxed requirements for pattern precision. Addressing these specific needs and opportunities, we attempted to use the inherent micro/nano-level self-structuring of polymeric materials when exposed to large energies provided by laser micron-size focused beams. The proposed system comprises a layered system of a very thin, tens to hundreds nm thick, metal layer that is opaque to the laser light deposited on a transparent polymer. For this system, which allows the confinement of the polymer thermal processes in a micron-wide, sub-micron thick volume, we mapped the correlation between the microablation process parameters and material properties, on one hand, and the resolution and profile of the patterned micro/nano-structures, on the other. It has been found depending on the choice of polymer, metal and laser energies, one can obtain different sub-micrometre polymer profiles, ranging from domes to ripples and holes. We also probed the use of this technology for the fabrication of biomedical microdevices that require spatial addressable immobilisation of proteins, such as microarrays, biosensors and lab-on-a-chip devices, and found that the microablation can induce the selective adsorption of proteins on patterned surfaces.