  Polymer filaments form the foundation of biology from cell scaffolding to
DNA. Their study and fabrication play an important role in a wide range of
processes from tissue engineering to molecular machines. We present a simple
method to deposit stretched polymer fibers between micro-pillars. This occurs
when a polymeric drop impacts on and rebounds from an inclined superhydrophobic
substrate. It wets the top of the pillars and pulls out liquid filaments which
are stretched and can attach to adjacent pillars leaving minuscule threads,
with the solvent evaporating to leave the exposed polymers. We use high-speed
video at the microscale to characterize the most robust filament-forming
configurations, by varying the impact velocity, substrate structure and
inclination angle, as well as the PEO-polymer concentration. Impacts onto plant
leaves or randomized nano-structured surface leads to the formation of a
branched structure, through filament mergers at the free surface of the drop.
SEM shows the deposition of filament bundles which are thinner than those
formed by evaporation or rolling drops. Raman spectroscopy identifies mode B
stretched DNA filaments from aqueous-solution droplets.
