Non-collapsible PDMS nanochannel fabrication with tunable width and height using single master mold

A tunable polydimethylsiloxane (PDMS) nanoslit fabrication process was developed for biological sample manipulation. A microcontact printing (μCP) of laterally spreading self-assembled hexadecanethiol (HDT) layer, combined with in-situ curing of a sliding SU-8 droplet, enabled precise and independent tuning of a nanoslit-mold width and height using single μCP master mold. The SU-8 nanoslit-mold was replicated using a hard-soft composite PDMS to prevent channel collapse at low (<;0.2) aspect ratio (height over width). The fluidic characteristics as well as dimensions of nanoslits fabricated with various conditions are analyzed using fluorescein sample and AFM images. Finally, concentration polarization-based sample preconcentration is successfully demonstrated at the nanoslit boundary where an electric double layer is overlapped.