Pillar-structured 3D inlets fabricated by dose-modulated e-beam lithography and nanoimprinting for DNA analysis in passive, clogging-free, nanofluidic devices.

We present the fabrication of three-dimensional inlets with gradually decreasing widths and depths and with nanopillars on the slope, all defined in just one lithography step. In addition, as an application, we show how these micro- and nanostructures can be used for micro- and nanofluidics and lab-on-a-chip devices to facilitate the flow and analyze single molecules of DNA. For the fabrication of 3D inlets in a single layer process, dose-modulated electron beam lithography was used, producing depths between 750 nm and 50 nm along a 30 μm long inlet, which is additionally structured with nanometer-scale pillars randomly distributed on top, as a result of incomplete exposure and underdevelopment of the resist.