Two Nanomaterials Are Coming In The Way

Sharon M. Weiss is an associate professor of electrical engineering with Vanderbilt has led a team to  invent a new production system to produce porous nanomaterials, the new system is much cheaper, it is also much more easier and more quicker.

The idea is to create a master stamp for mass production of the nanomaterials, by involving a coating for the nanoporous surface with a resist during the manufacturing of the nanomaterial, using UV light or a laser beam to create the desired pattern, then subject the material to a series of chemical treatments then stamp out copies by a process called direct imprinting of porous substrates (DIPS).

The team’s first creation was a biosensor, that can identify organic molecules such as DNA, proteins and viruses. It features a grating made from porous silicon, that can be treated so that a target molecule will stick to it. If that molecule is present in a liquid sample, then it will cause laser light shined on the grating to diffract in a specific pattern.

They have since used DIPS to create highly-sensitive chemical sensors, and to produce shaped microparticles – this is done by using the stamp to cut right through the porous nanomaterial, like a cookie cutter. Microparticles made from porous silicon could find use as anodes in lithium-ion batteries, which would have a higher capacity than conventional li-ions, but not much more weight.

On another direction  Jörg Weißmüller, a materials scientist at the Technical University of Hamburg and the Helmholtz Center Geesthacht, has been working in cooperation with colleagues from the Institute for Metal Research in Shenyang, China, and they have reached to discover a  new metallic high-performance material.

In order to produce this innovative material, material scientists employ a comparatively simple process: corrosion. The metals, typically precious metals such as gold or platinum, are placed in an acidic solution. As a consequence of the onset of the corrosion process, minute ducts and holes are formed in the metal. The emerging nanostructured material is pervaded by a network of pore channels.

The pores are impregnated with a conductive liquid, for example a simple saline solution or a diluted acid, and a true hybrid material of metal and liquid is thus created. It is the unusual “marriage”, as Weißmüller calls this union of metal and water which, when triggered by an electric signal, enables the properties of the material to change at the touch of a button.As ions are dissolved in the liquid, the surfaces of the metal can be electrically charged. In other words, the mechanical properties of the metallic partner are changed by the application of an electric potential in the liquid partner. The effect can be traced back to a strengthening or weakening of the atomic bonding in the surface of the metal when extra electrons are added to or withdrawn from the surface atoms. The strength of the material can be as much as doubled when required. Alternatively, the material can be switched to a state which is weaker, but more damage tolerant, energy-absorbing and malleable. Specific applications are still a matter for the future.

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