Fabrication of nanofluidic channels in polymer substrates using nanomechanical probes

In the past, researchers have struggled to directly create nanochannels in polymer substrates using Atomic Force Microscope (AFM) probes (i.e., nanomechanical probes) due to the inability of the probes to 'scratch' substrates with insufficient surface hardness. We will present in this paper a novel process for the fabrication of polymer-based encapsulated nanofluidic channels using nanomechanical probes. Essentially, a nanomechanical probe is first used to create nanochannel molding features of various widths and heights on polymethyl methacrylate (PMMA) substrates (which have sufficiently high hardness for probes to scratch nanochannels). Then, Polydimethylsiloxane (PDMS) is used twice to mold-out concave nanochannels from the nanochannel features on PMMA substrate. Making nanochannels in PDMS substrates is important due to PDMS's biocompatibility and ability to create strong interfacial bonding after treatment with oxygen plasma. From the experimental results, gold nanoparticle (∼50 nm diameter) solution mixed with pure ethanol was shown to flow in the nanofluidic channel system, proving that this novel technology could eventually be used for the study of nanofluidics and transport of single macromolecule or DNA in fluidic media.