Nanofluidics

More fundamental in nature is the study of molecular transport through conduits with nanometer scale dimensions, what we refer to as nanofluidics. We are studying both fluid and polymer transport through individual nanoscale conduits or pores that are top-down fabricated in hard materials such as glass, quartz or silicon. We are attempting to further reduce lateral dimensions of channels and pores utilizing bottom-up strategies and interfacing molecular assemblies to features formed in hard materials. One research program for achieving the goal of sequencing single molecules of DNA using transverse conductance probes located in a nanoscale channel is under investigation in our laboratory. We believe, based upon quantum-mechanical calculations performed by our collaborator, Max Di Ventra, UCSD, that the individual nucleotides making up a single strand polynucleotide can be distinguished by measuring the electron tunneling current through the individual monomeric units perpendicular to the polymer backbone, see Figure 1^{1, 2}. The execution of this measurement strategy requires the development of at least two technological capabilities; the formation of nanometer scale fluidic channels for the localization of the polynucleotide and the formation of opposed conductance probes within these channels with nanoscale spacing and lateral extent. Nanoscale in the context of these experiments must truly be of molecular scale, in the range of ≈ 1-2 nm. A combination of bottom-up and top-down nanofabrication strategies will be explored for the fabrication of devices that will allow demonstration of proof-of-principle concepts and further refinement to achieve single nucleotide resolution.