Further more about Nanotechnology

Carbon nanotubes

 

 

     

Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1,^[1] which is significantly larger than any other material. These cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science, as well as potential uses in architectural fields. They exhibit extraordinary strength and unique electrical properties, and are efficient thermal conductors. Their final usage, however, may be limited by their potential toxicity and controlling their property changes in response to chemical treatment.
Nanotubes are members of the fullerene structural family, which also includes the spherical buckyballs. The ends of a nanotube might be capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 1/50,000th of the width of a human hair), while they can be up to several millimeters in length (as of 2008). Nanotubes are categorized as single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
The nature of the bonding of a nanotube is described by applied quantum chemistry, specifically, orbital hybridization. The chemical bonding of nanotubes is composed entirely of sp² bonds, similar to those of graphite. This bonding structure, which is stronger than the sp³ bonds found in diamonds, provides the molecules with their unique strength. Nanotubes naturally align themselves into "ropes" held together by Van der Waals forces.

Applications of nanotubes

·         Nanotubes bound to an antibody that is produced by chickens have been shown to be useful in lab tests to destroy breast cancer tumors. The antibody carrying nanotubes are attracted to proteins produced by a one type of breast cancer cell. Then the nanotubes absorb light from an infrared laser, incinerating the nanotubes and the tumor they are attached to.

·         Lightweight windmill blades made with an epoxy containing carbon nanotubes. The strength and low weight provided by the use of nanotube filled epoxy allows longer windmill blades to be used. This increases the amount of electricity generated by each windmill.

·         Aircraft using carbon nanotubes to increase strength and flexibility in highly stressed components.

·         Nanotube electrodes in thermo cells that generate electricity from waste heat.

·         Inexpensive nanotube based sensor that detects bacteria in drinking water. Antibodies sensitive to the particular bacteria are bound to the nanotubes, which are then deposited onto a paper strip. When the bacteria is present it attaches to the antibodies, changing the spacing between the nanotubes and the resistance of the paper strip containing the nanotubes.

·         Combining carbon nanotubes, bucky-balls and polymers to produce inexpensive solar cells that can be formed by simply painting a surface.

·         A lightweight, low power anti-icing system using carbon nanotubes in a layer coated onto aircraft wing surfaces.

·         Using gold tipped carbon nanotubes to trap oil drops polluting water.

·         Building transistors from carbon nanotubes to enable minimum transistor dimensions of a few nanometers and developing techniques to manufacture integrated circuits built with nanotube transistors.

·         Strong, lightweight composites of carbon nanotubes and other materials that can be used to build lightweight spacecraft.

·         Cables made from carbon nanotubes strong enough to be used for the Space Elevator to drastically reduce the cost of lifting people and materials into orbit.

·         Using nanotubes as a cellular scale needle to deliver quantum dots and  proteins into cancer cells.

·         Ultra capacitors using nanotubes that may do even better than batteries in hybrid cars.

·         Improve the healing process for broken bones by providing a carbon nanotube scaffold for new bone material to grow on.

·         Sensors using carbon nanotube detection elements capable of detecting a range of chemical vapors. These sensors depend upon the fact that the resistance of a carbon nanotube changes in the presence of a chemical vapor.

·         Static dissipative plastic molding compounds containing nanotubes that can be used to make parts such as automobile fenders that can be electro statically painted.