This paper presents a cost-effective approach for the template-assisted electrodeposition fabrication of substrates for surface-enhanced Raman scattering (SERS) with metal nanowires (NWs) grown in pores of polymer track-etched membranes (TM). This technique allows the synthesis of NWs array with its certain surface density and diameter (from dozen to hundreds of nm). NWs length also may be varied (order of μm) by controlling deposition time. Here we grow vertical Ag-NWs which are leaning towards their nearest neighbors, forming self-assembled bundles whose parameters depend on the NW aspect ratio (length to diameter). We show that in such bundles there are “hot spots” in the nm-gaps between NWs tips. Computer simulations have demonstrated a strong enhancement of the electric field within these hot spots; thus, the Raman signal is markedly amplified for analyte molecules placed directly inside the gaps. We have experimentally proved the potential of this SERS-technique on the example of 4-Mercaptophenylboronic acid (4-MPBA). For 4-MPBA the maximal enhancement of Raman signal was found at NWs length of ~1.6 μm and diameter of ~100 nm. The effect is higher (up to twice) if “wet” substrate is used just immediately after the TM polymer removal so that the tips are brought to lean after analyte exposure. We suggest this new type of nanostructured SERS-substrates as a base of effective sensing of extremely low concentration of analytes.

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Barrier contactless dielectrophoresis is proposed as a method for microbiological particle separation. Design of a separation device for barrier contactless dielectrophoresis is discussed. The principle of separation device is based on formation of barriers of gradient fields in the volume of separation chamber by electrodes with passivation dielectric coating of silicon carbide. A feature of the method is absence of contact between separated samples and conductive elements of electrode structure. The proposed method is highly efficient and easy to use in comparison with dielectrophoresis on isolated structures and conventional planar systems. Computer simulation of electric field distribution over dielectrophoretic barriers is carried out, and effect of the thickness of the passivation coating on dielectrophoretic properties of barriers is shown. Forces acting on a particle (a yeast cell with a diameter of 7 μm) in separation chamber are evaluated using computer simulation data. Ability of the cell to be captured by the method of contactless barrier dielectrophoresis is theoretically predicted and confirmed experimentally, using yeast cells. The yeast cells subjected to positive dielectrophoresis can be effectively captured (up to 90%) by the separation device at the applied voltage of 20 V and 100 kHz and at flow rate of 20 mL/h.

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