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Fabrication of Metallic Nanowires

  The development of more powerful electronic, magnetic, photonic and sensing devices depends on continued progress in miniaturizing their components. Currently, efforts are focused on building nanoscale structure or building blocks. Most of the building blocks in electronic devices are made of metal wires, acting as electron conductive interconnects and functional units. It is necessary to scale down the metal wires making them into nanowires.

Metal nanowires, one-dimensional (1D) nanostructures, are molecular metallic wires, millions of times smaller in diameter than a human hair. Although these wires are so tiny, they still have high rates of electron transfer with low resistance, which means less impedance to the flow of current with little loss of energy. They also have unique magnetic, optical, mechanical properties as well as chemical and thermal stabilities, making them a promising material in many applications.

    Conventional technologies for nanowire fabrication are based on the "top-down” approach, such as the photolithographic method; they have reached their limits. Although present electrochemical methods can produce large amounts of long, free standing and uniform nanowires, the manipulation problems pose severe limitations. The alternative “bottom up” approach based on biomolecular templates can solve the manipulation problems, but it has proved difficult to fabricate continuous metallic nanowires with good electric conductivity. Among many biomolecular templates, peptides are good candidates for nanowire fabrication. They can form more stable complexes with metal ions. They have more functional residues to interact with metal ions and with electrodes to be bridged. They are also stable at a wide range of pHs, temperatures, and concentrations. The morphology of their self-assembled nanostructures can be controlled by changing peptide sequence, substrates and solution conditions including solvent, pH, ionic concentration, temperature and light.

Our objective is to develop a new peptide-template based approach to fabricate metallic nanowires with good electron conductivity at desired locations.

AFM image of a designed peptide self-assembled nanostructure on HOPG