Invention: Carbon nanotubes
Carbon nanotubes are ultra-small, cylindrical molecules that can only be seen under powerful microscopes, but catching a glimpse of one is like seeing into the future. Discovered by Sumio Iijima at Japan’s NEC Corporation, they are the hardest substance known to humankind and 1,000 times more conductive than copper. Carbon nanotubes could usher in a new era in which computers are faster and materials stronger than ever thought possible.
Imagine carbon atoms, each joined to three neighbouring atoms, in a hexagonal or honeycomb pattern to form a sheet just one atom thick. Now imagine that sheet rolled so that the edges join to form a cylinder – a carbon nanotube. These tubes might be singular (so-called single-walled) or comprise two or more concentric tubes of different diameters – one inside another (so-called multi-walled). Carbon nanotubes may have diameters of just a few nanometres but lengths that can reach several millimetres – like minute bits of string.
Although award-winning physicist Sumio Iijima might modestly credit his discovery of multi- and single-walled carbon nanotubes to good fortune, their unearthing was much more the culmination of years of research and hard work than pure luck. From developing a specialized high-resolution electron microscope, while still an undergraduate student, to years spent researching atomic structures of materials such as carbon, Iijima was in a unique position to make one the biggest discoveries in material sciences over the last few decades.
Societal benefit
Iijima’s discovery shook the foundations of his field. Until he identified nanotubes, pure carbon was believed to only exist in three forms: diamonds, graphite and the hollow, ball-shaped fullerenes. The identification of carbon nanotubes sparked newfound attention in Iijima’s field and since then, a myriad of uses have been found for these super-thin yet highly conductive molecules.
Carbon nanotubes have formerly unknown electrical and thermal properties. They are much more conductive than copper, and they have found a variety of chemical, mechanical and optical applications. Many materials, including polymers and metals, can be significantly improved by using carbon nanotubes as filler: They render solar panels more effective and automotive and airplane parts more robust, for example.
Economic benefit
The commercialisation and market introduction of carbon nanotubes is in full swing, but currently limited to the use of bulk nanotubes – that is to say, a mass of unorganised nanotubes used as composite fibres in polymers to bolster their mechanical, thermal and electrical properties.
Carbon nanotubes have formerly unknown electrical and thermal properties. They are much more conductive than copper, and they have found a variety of chemical, mechanical and optical applications. Many materials, including polymers and metals, can be significantly improved by using carbon nanotubes as filler: They render solar panels more effective and automotive and airplane parts more robust, for example.
How it works:
Two electrodes – rods of graphite, a pure form of carbon – are inserted into the chamber, and an electric charge is applied. When the two rods are brought close together, the intense energy of the resulting spark vaporises one of their tips. Upon examination of the other rod’s tip, one finds that microscopic, stringy protrusions have formed, resembling a tousled head of hair. Those protrusions are carbon nanotubes, specifically multi-walled ones that typically contain 20-30 walls. If a metal catalyst is included in the positively charged graphite rod (the anode) then single-walled carbon nanotubes form.
The inventor:
Iijima is a professor at Meijo University in Nagoya and continues to work as a Senior Research Fellow at NEC Corporation. He is also an honorary fellow at Japan’s National Institute of Advanced Industrial Science and Technology,.