Sponser's Link

Archives

Live Feeds

Visitor Counter

SEARCH BOX

Showing posts with label nanotubes. Show all posts

Nanomembranes are commonly made from organic polymer based nanocomposites with a thickness less than 100nm. Such nanomembranes include organic polymers combined with a mesh of silica nanoparticles. The size of the holes in the mesh restricts or allows the passage of different sized molecules.

Nanomembranes are commonly fabricated using Layer-by-Layer (LbL) assembly methods. This method give precise control over the in plane composition of the membrane and allows for the addition of a range of components to be added to the membrane. These components include nanoparticles and nanotubes that can tailor the mechanical, optical and electronic properties of the nanomembrane.

Applications for nanomembranes include :
  • Desalination of sea water
  • Purification of polluted water
  • Removal of carbon dioxide and other pollutants from exhaust gases
  • Sensors in MEMS
  • Carbon Nanomembranes

CNMs:
Carbon nanomembranes (CNMs) are similar to plastic films, but only 1 nanometer (1 millionths of 1 millimeter) in thickness. CNMs are the thinnest man-made polymeric membranes. Their thickness is fifty times thinner than commercial inorganic membranes and about five times thinner than biological lipid bilayers. CNMs constitute a new class of material with interesting properties that promise to lead to innovative products in many fields:
  • CNMs are 1 nm thin, mechanically stable – yet elastic – carbon-based films.
  • CNMs can be transferred to various surfaces or micro structures - including TEM-grids - to form free standing two-dimensional layers.
  • The two sides of CNMs can be chemically and biologically functionalized.
  • CNMs can be transformed into a single layer graphene.
  • Mechanical and chemical patterning of CNMs is possible according to customer specifications.
  • Perforation and chemical functionalization of CNMs allows nano-filtration.
  • Integration of CNMs into silicon chips or micro‑electromechanical systems (MEMS) is demonstrated.
  • Conductivity of CNMs can be tuned from insulating to conductive during production.

The Nanowire is a solid, cylindrical wire with a diameter usually less than 100 nm.Fabrication of Nanowires at surfaces.Nanowires are just like normal electrical wires other than the fact that they are extremely small. Like conventional wires, nanowires can be made from a variety of conducting and semiconducting materials like copper, silver, gold, iron, silicon, zinc oxide and germanium. Nanowires can also be made from carbon nanotubes.

The goal of this project is the design of artificial materials that consist of ultrafine wires or linear arrays of dots, ten to hundred times finer than those produced with commercial micro-structure fabrication techniques. In fact, we have gone all the way down to atom chains which may be viewed as the ultimate nanowires (scroll to the bottom for those). These patterns are formed by self-assembly, where atoms arrange themselves naturally at stepped silicon surfaces.

An important aspect in fabricating nanowires is the ability to prepare wires of an any material on any substrate with any thickness. In particular, using silicon wafers as substrate is highly-desirable. To achieve this goal we suggest the following "universal" process. First, a silicon substrate with a regular array of steps is prepared (A). Then, stripes (B) or dots (C) of a passivating material are attached to the step edges. This part is analogous to creating a photoresist mask in traditional lithography. As mask material we use calcium fluoride, which is lattice-matched to silicon and chemically inert. Eventually, the desired material is deposited on the remaining silicon, for example by substrate-selective chemical vapor deposition (CVD) or electroplating. Alternatively, calcium fluoride could become useful as an etch mask for producing trenches in the silicon that can be filled with new materials to achieve a planar structure.

Applications:
Nanowires show promise for use in applications including:

•        Exceptionally small electronic circuits

•        Memory devices

•        Transistors

•        Advanced composite materials

•        Quantum devices

•        Biomolecular nanosensors

•        MEMS

•        Optoelectronics

•        Field Emitters

•        Photon Ballistic Waveguides

Sponser's Link