Isolated, sealed nanofluidic channels formed by combinatorial-mould nanoimprint lithography

We present a new approach for fabricating isolated, sealed, high-density nanofluidic channel arrays using combinatorial-mould nanoimprint lithography. This method provides a directed stamping technique for fabricating micro- to nanoscale channel arrays from the simple combination of two grating moulds of the proper geometry. In this method, a thin polymer film is cast on a silicon grating mould and subsequently embossed with a second grating mould. The film, after it is patterned on both sides, is then stamped onto a substrate and etched with oxygen plasma to remove the suspended residue layer and isolate the nanochannels. We have successfully fabricated arrays of high-density nanochannels on silicon and indium tin oxide glass (ITO glass) with well-controlled dimensions (i.e. 250 nm square, in cross-section). Placing a nanochannel array in contact with an aqueous fluorescein solution fills the channels by capillary action, and the integrity of the seal formed by the nanochannel enclosures was verified by observing a significant contrast in the photobleaching rate under fluorescence microscopy.