Fabrication of polydimethylsiloxane (PDMS) nanofluidic chips with controllable channel size and spacing

The ability to create reproducible and inexpensive nanofluidic chips is essential to the fundamental research and applications of nanofluidics. This paper presents a novel and cost-effective method for fabricating a single nanochannel or multiple nanochannels in PDMS chips with controllable channel size and spacing. Single nanocracks or nanocrack arrays, positioned by artificial defects, are first generated on a polystyrene surface with controllable size and spacing by a solvent-induced method. Two sets of optimal working parameters are developed to replicate the nanocracks onto the polymer layers to form the nanochannel molds. The nanochannel molds are used to make the bi-layer PDMS microchannel-nanochannel chips by simple soft lithography. An alignment system is developed for bonding the nanofluidic chips under an optical microscope. Using this method, high quality PDMS nanofluidic chips with a single nanochannel or multiple nanochannels of sub-100 nm width and height and centimeter length can be obtained with high repeatability.