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A Focused Ion Beam (FIB)-patterned silicon mould is used to fabricate elastomeric nanostructures, whose cross-section can be dynamically and reversibly tuned by applying a controlled mechanical stress. Direct-write, based on FIB milling, allows the fabrication of nanostructures with a variety of different geometries, aspect ratio, spacing and distribution offering a higher flexibility compared to other nanopatterning approaches. Moreover, a simple double replication process based on poly(dimethylsiloxane) permits a strong reduction of the fabrication costs that makes this approach well-suited for the production of low cost nanofluidic devices. DNA stretching and single molecule manipulation capabilities of these platforms have been successfully demonstrated. [ABSTRACT FROM AUTHOR]

Polymeric nanofluidic structures are good candidates for boosting the exploitation of the powerful functionalities offered by nanofluidics in many fields. The advantages offered by polymeric materials are mainly related to their low cost and ease of manufacture, compared to semiconductor industry-derived materials. When the size of functional structures is shrunk from micro to nanoscale, the limits of these materials become evident. In particular, polydimethylsiloxane (PDMS) nanostructures (nanochannels or nanoslits) experience problems of collapse during the sealing process. In this work, we propose a junction gap breakdown-based approach to fabricate polymeric nanoporous networks in situ, i.e. at the tip of an asymmetric microfunnel made of commercial PDMS. We show that these micro/nanofluidic structures have ionic current rectification characteristics, even when filled with high ionic strength solutions (1 M KCl). Moreover, analyzing the electro-kinetic transport properties of these PDMS micro/nanostructures filled with fluorescent solutions, we observed at negative bias an intra-funnel accumulation. This phenomenon results much stronger for low ionic strength solutions. As these devices combine ease of fabrication, with interesting electrical properties, they are good candidates as functional structures in many fields, spanning from biomedical applications, where they can support the development of high-sensitivity sensors, to desalination applications and ionic circuits. [ABSTRACT FROM AUTHOR]