The paper describes a reliable technique to prepare PDMS membrane used to determine the permeability to CO2 and He. SEM controls morphology of surface membrane and SEM/FIB measures the membrane thickness. The data show that permeability becomes thickness dependent below some tens of micrometers. The Islam׳s model, based on the non-equilibrium sorption–desorption process at the interface, fits quite well with the experimental data. The comparison shows that flux models based on interface reaction could apply to describe quantitatively the thickness-dependence of the permeability. The model allows to determine the surface reactions rate constants for CO2 and He on PDMS. The introduction of a specific characteristic thickness Lc provides a functional form, which describes very accurately the results of the present paper and other experiments on polymers. By reducing the membrane thickness below 200nm, both permeability and selectivity change, indicating Knudsen diffusion as flux mechanisms responsible for permeation. In this range of thickness, SEM images reveal membrane defects

We present the development and the electrical characterization of a polymeric nanochannel device. Standard microfabrication coupled to Focused Ion Beam (FIB) nanofabrication is used to fabricate a silicon master, which can be then replicated in a polymeric material by soft lithography. Such an elastomeric nanochannel device is used to study DNA translocation events during electrophoresis experiments. Our results demonstrate that an easy and low cost fabrication technique allows creation of a low noise device for single molecule analysis.

Several strategies have been developed for the control of DNA translocation in nanopores and nanochannels. However, the possibility to reduce the molecule speed is still challenging for applications in the field of single molecule analysis, such as ultra-rapid sequencing. This paper demonstrates the possibility to alter the DNA translocation process through an elastomeric nanochannel device by dynamically changing its cross section. More in detail, nanochannel deformation is induced by a macroscopic mechanical compression of the polymeric device. This nanochannel squeezing allows slowing down the DNA molecule passage inside it. This simple and low cost method is based on the exploitation of the elastomeric nature of the device, can be coupled with different sensing techniques, is applicable in many research fields, such as DNA detection and manipulation, and is promising for further development in sequencing technology.

The lack of engineering systems able to faithfully reproduce complex kidney structures in vitro has made it difficult to efficiently model kidney diseases and development. Using polydimethylsiloxane (PDMS) scaffolds and a kidney-derived cell line we developed a system to rapidly engineer custom-made 3D tubules with typical renal epithelial properties. This system was successfully employed to engineer patient-specific tubules, to model polycystic kidney disease (PKD) and test drug efficacy, and to identify a potential new pharmacological treatment. By optimizing our system we constructed functional ureteric bud (UB)-like tubules from human induced pluripotent stem cells (iPSCs), and identified a combination of growth factors that induces budding morphogenesis like embryonic kidneys do. Finally, we applied this assay to investigate budding defects in UB-like tubules derived from a patient with a PAX2 mutation. Our system enables the modeling of human kidney disease and development, drug testing and discovery, and lays the groundwork for engineering anatomically correct kidney tissues in vitro and developing personalized medicine applications.

Iodine $\left({\mathrm{I}}_2\right)$ -assisted, $30\mathrm{keV}$ ${\mathrm{Ga}}^{+}$ focused ion beam (FIB) has been employed to fabricate nanogap Au electrodes and has been compared to conventional FIB milling. Electrical characterization shows that ${\mathrm{I}}_2$ assistance improves insulation resistance from $300–400\mathrm{G}\Omega \text{to}20–50\mathrm{T}\Omega$ . Auger depth profiling reveals that the Ga concentration profile in FIB-milled samples has a peak value of $25\mathrm{at.}\%$ at $7\mathrm{nm}$ and extends, with a decreasing Gaussian tail, down to $40\mathrm{nm}$ , whereas in ${\mathrm{I}}_2$ -processed samples Ga concentration is reduced below $5\mathrm{at.}\%$ . ${\mathrm{I}}_2$ assistance is found to increase minimum gap size from $8\text{to}16\mathrm{nm}$ and to markedly roughen Au surface morphology.

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.