As nanotechnology continues to emerge as the scientific beacon of the future, carbon nanotubes (CNTs) are no exception. Carbon nanotubes are 100 times stronger than steel but at one-sixth the weight. They also conduct heat and electricity better than copper. Harnessed properly, the applications of CNTs are revolutionizing material science and technology.
Current Applications of Carbon Nanotubes
CNTs have been making quite an impression on commercial products for some time now. Carbon nanotubes are already being used to control or enhance conductivity in polymers and are added to anti-static packaging. The most popular current use for CNTs is structural reinforcement. They are added to other materials like rebar to concrete because of their high strength, low weight, and flexibility. CNT production is also used in bulk composite materials and thin films.
Multi-walled nanotubes (MWNTs) were first used as electrically conductive fillers in plastics. Today, they are also used to enhance fiber composites. Examples include wind turbine blades and hulls for maritime security boats. By 2005, 50% of lithium batteries incorporated carbon nanofibers, which are wires spun from CNTs. Carbon nanotubes are even being used to enhance sporting goods like tennis rackets, baseball bats, and bicycle frames.
Potential Applications of Carbon Nanotubes
Because carbon nanotubes are highly electrically conductive, they have the ability to be a cost-effective replacement for metal wires. Their semiconducting properties make them candidates to replace existing computer chips. In the future, CNTs will likely compete with carbon fiber for high-end uses, particularly in weight-sensitive applications such as Kevlar. Additionally, CNTs have been found to be a more environmentally-friendly, flame-retardant additive to plastics. MWNT-containing paints have also been found to reduce biofouling of ship hulls, discouraging the attachment of algae and barnacles, making it an environmental alternative to hazardous, biocide-containing paints.
Researchers from the University of North Carolina say that their nanotube-based imaging system could take sharper, faster pictures than today’s X-rays or CT scans. Other researchers have discovered that bundles of CNTs doped with nitrogen form a more efficient and compact catalyst for hydrogen cars than a platinum one. Chinese researchers have created flexible, paper-thin speakers out of nanotube sheets. Unlike conventional speakers, which make noise by vibrating the surrounding air molecules, these CNT speakers use the thermoacoustic effect (similar to how lightning produces thunder) where an electric current runs through the nanotube sheets, heating and expanding the air near them, creating sound waves. These speakers aren’t the only bendable electronics that can be made with CNTs. Researchers at the University of Tokyo constructed a display made of organic light-emitting diodes (OLEDs) paired with a rubbery, nanotube-based conductor.
CNTs in Medicine
Carbon nanotubes are even emerging in the medical field. Spanish researchers have created a biosensor that can diagnose yeast infections quicker than the current method. When the transistor containing CNTs and antibodies programmed to attack the Candida yeast cells is put in contact with a cell sample, the interaction between the yeast and the antibodies changes the electric current of the device.
Another potential medical application of CNTs is in helping to target tumors. Researchers injected CNTs into kidney tumors in mice and directed a near-infrared laser at the tumors. The tubes responded by vibrating, which created enough heat to kill the surrounding tumor cells.
The biggest hindrance to the expansion of commercial CNT use is the cost of production, but that is predicted to change. Since 2006, CNT production capacity has increased ten folds. In 2009, researchers from the University of Dayton, Ohio noted that nanotube production costs had fallen 100 folds since 1990. In 2005, it was predicted by Cientifica that by 2010, carbon nanotube prices would decrease by a factor of 10-100, that the global market for nanotubes would surpass €3 billion, and that Korea would be the major supplier of all types of nanotubes. Now, it is predicted that the global market will reach 5.64 billion USD by 2020. Hopefully, carbon nanotubes will continue this trend toward cost effectiveness.
