Plasma thinned nanopost arrays for DNA electrophoresis

Separating long DNA in a microfabricated post array requires (tens of) thousands of posts in the separation channel. Moving from microposts to nanoposts is thus a fabrication challenge owing to the large area that needs to be nanopatterned. The authors implemented an oxygen plasma etching method in conjunction with conventional optical photolithography and deep trench etching that led to centimeter-long microchannels containing either 360 or 460 nm diameter posts in a hexagonal array with a 3 μ m spacing. Separations of the XhoI λ -DNA digest in the device indicate that these sparse nanopost arrays are an improvement over the equivalent micropost array with only a marginal increase in fabrication cost. The fabrication method described here is broadly applicable to biological microfluidic and nanofluidic platforms that require nanoscale features with micrometer-scale spacing.