On-demand electrophoretic separation of DNA in written gel lines on planar substrates

We report a new approach to perform on-demand electrophoretic separation of DNA. In contrast to standard chip-based capillary electrophoresis in micromachined glass chips, we apply a planar polyimide substrate, write 200 μm wide gel lines bridging two Pt-electrodes and inject 500 pl sample volumes in non-contact manner. The gel is covered with mineral oil to inhibit evaporation. Subsequently, an electrical field is applied for 80 s and the separation of the DNA molecules (56 bp-Cy5 and 112 bp-Cy5, 10 μM) is successfully demonstrated.