Tiny tubes, huge potential


With his 1991 discovery of carbon nanotubes – ultrathin, highly conductive molecular structures consisting of miscroscopic carbon fibres, Japanese researcher Sumio Iijima sparked a materials science revolution. Previously, pure carbon had only been known to exist in three forms: diamonds, graphite, and hollow, spherical fullerenes.

Research conducted by Iijimia and his team revealed that carbon nanotubes (CNTs) are not only the fourth type of pure carbon, they’re also the hardest substance known to humankind, highly flexible, and 1000 times more conductive than copper. Their discovery unlocked an entire field of research, and with it innumerable applications for the groundbreaking nanomaterial.

Iijima’s pioneering innovation has earned him a 2015 European Inventor Award in the Non-European countries category. Patented by technology company NEC, it is already celebrated on the world market: Currently, 100 companies across the globe are manufacturing carbon nanotubes. In 2010, the industry saw an annual turnover of 552.3 million euros; by 2016, this number is expected to rise to 912.6 million.

Here, you can discover some of the promising applications for the tiny tubes with the enormous potential.

Nano-electrodes venture deep into the brain

Neuroscientists at Rice University in Houston, Texas, have developed a CNT-based alternative to conventional metal electrodes for Deep Brain Stimulation (DBS). Due to carbon nanotubes’ high conductivity, this new generation of nano-electrodes is capable of amazing feats: They don’t only carry electric impulses into the brain but also transmit “responses“ back from the organ’s neural circuitry.

While conventional electrodes only transport electricity in one direction, the new “two-way” electrodes provide valuable diagnostic insight from the deep reaches of the brain, in real time. What’s more, because their nanostructure makes them highly flexible, these electrodes also reduce the number of infections that can impair the effectiveness of DBS treatments.

“Super”-strong spider silk through carbon nanotubes

Spiderman would be jealous: A team of researchers at the University of Trento, Italy, used carbon nanotubes to create “super-strong” spider silk proteins, rendering the fibres spun by Pholcidae spiders (more commonly known as daddy longlegs) three times as robust as natural spider silk.

Nanotubes; picture licensed by Csiro, http://www.scienceimage.csiro.au

Tests conducted by the MIT Technology Review showed that the super-silk surpassed even Kevlar, the material used in bulletproof vests, in terms of tear resistance.

The Italian scientists’ method also seems straight out of a Spiderman comic: The researchers created their “super-spiders” simply by spraying them with water containing carbon nanotubes and ultra-hard graphene particles. And although they still need to investigate the exact natural mechanisms that led to their success, the team is already dreaming up some seemingly fantastical applications, including a “super-net” that catches planes before they crash.

“Paper batteries” and origami

Short-lived batteries might soon be a thing of the past thanks to nanotubes’ extremely high conductivity. Researchers at the Arizona State University have built a battery from cellulose – also known as paper – covered with a 0.33 millimetre-thin coating of carbon nanotubes. On its smooth surface, the innovative lithium ion “paper” battery combines characteristics of a long-lasting battery and a super capacitator, holding its charge much longer than conventional batteries.

The highlight: If the paper battery is folded according to the so-called Miura technique – developed by Japanese astrophysicist Koryo Miura for folding solar panels in the space industry – its charge density increases by a factor of 14. The answer to the battery crisis could be carbon nanotubes…and origami.

Microchips drawn with “nano-ink”

Sumio Iijima

The microchips of the future might be drawn by hand. Researchers at Beijing’s Tsinghua University have developed a method for drawing complex patterns on circuit boards using a pen and carbon nanotube ink. Compared to semiconductor materials such as gold and silver, carbon nanotubes are quite inexpensive, not to mention highly conductive and capable of being applied in multiple layers.

The Chinese scientists’ “ink” combines carbon nanotubes with a solution made from polyethylene oxide (PEO), a viscous polymer. Because of PEO’s robust chemical structure, patterns with a length of up to 50 centimetres can be drawn with a pen. Last but not least, tests have shown the flexible material’s conductivity to increase by 30% when folded 1000 times –the perfect basis for a new generation of stretchy rubber microchips.

Aircraft parts “baked” with nanotubes

Nanotechnology could also revolutionise the large-scale processing of composite materials, for example in the manufacture of aircraft parts. Traditionally, heat-sensitive polymers in wing and fuselage components are merged using gigantic ovens, but researchers at the Massachusetts Institute of Technology (MIT) in Boston have come up with a gentler, more efficient alternative.

Their method involves wrapping the individual parts with a wafer-thin carbon nanotube coating. When an electric charge is applied, this coating starts producing enough uniformally distributed heat to fuse all types of polymer commonly used in aircraft manufacturing. The nanotubes, measuring only 400 microns, deliver a tremendous increase in efficiency compared to industrial ovens: The heat-producing nanocoating lowers energy consumption by a factor of 1000, cutting production costs in half – and ensuring “hot” prospects on the market.

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