Nanotechnology

Nanotechnology

Nanotechnology is about the deliberate fabrication of structures at the size scale of below a hundred nanometres. That’s about a fifth of the wavelength of light, and it’s where the physics starts to change.

Paul Callaghan, from Health and Science column, the New Zealand Listener, 3 December 2005

New Zealand’s third Nobel laureate, expat chemist Alan MacDiarmid (1927-2007), was one of the pioneers of nanotechnology. He shared the 2000 Nobel Prize in chemistry with Alan Heeger, at the time a physicist at the University of Pennsylvania, and Hideki Shirakawa, at the Tokyo Institute of Technology, together with whom he discovered that plastics could conduct electricity.

MacDiarmid was born the youngest of five children in 1927 in Masterton. During the Great Depression his father was out of work for four years, but the family nevertheless shared what they had with others less well off. Shortly after winning the Nobel Prize, MacDiarmid told one of his brothers how lucky he was to have grown up in a poor but loving family, which made him self-reliant and conscious of the value of money, but also taught him the important aspects of interpersonal relationships.

His interest in chemistry was inspired early, when he borrowed The Boy Chemist from the children’s section of his local library. His favourite experiment was making invisible ink, but he also learned to make his own fireworks, which meant that his family was the only one in the district to celebrate wartime Guy Fawkes night with a bang.

After leaving school at 16, MacDiarmid supported himself by working as a lab boy in the chemistry department at Victoria University College, where he discovered that he loved colour. Little did he know that preparing bright orange crystals of S₄N₄ - (sulphur nitride) would be his first step towards a Nobel Prize.

When size matters

Nanotechnology is multi-disciplinary, bringing together physics, chemistry, biology and engineering. It is the science of the ultra small, involving the manipulation of matter at the nanoscale – one billionth of a metre, or 80,000 times smaller than the width of a human hair. The director of the MacDiarmid Institute for Advanced Materials and Nanotechnology, Paul Callaghan, can foresee pragmatic results from nanotechnology, such as selfcleaning fabrics, scratch-free glass and super-strong but lightweight building materials, but also more far-fetched achievements such as bionic eyes, artificial organs and a bridge between machines and the human body, brain cells and computers.

Callaghan came to nanotechnology via his research on ‘gooey and squishy’ materials that are neither liquid nor solid. This interest led him to develop a new field of physics called nuclear magnetic resonance (NMR) microscopy, which allows researchers to observe biological processes in living tissue.

Research projects at the institute include the development of silicon nanowhiskers and nanowires, which provide new components for electronic devices, carbon nanotubes, which can conduct electricity or act as semiconductors, and new optical techniques to produce miniature devices such as micro-machines and increasingly smaller computer chips.

Harnessing the sun’s power

The sun fires almost 40,000 times as much energy to Earth than we use. With a growing population, providing energy to people will be one of the most pressing problems in the future, yet an efficient and affordable use of solar energy remains a challenge. Not so for plants, and David Officer’s team at Massey University’s Nanomaterials Research Centre is taking inspiration from photosynthesis to harness the sun’s power.

Officer is investigating the light-harvesting qualities of a group of complex ring-shaped molecules called porphyrins, which can be activated by particular wavelengths. His team aims to develop nano-structured solar cells, using porphyrins and conducting plastics.

Limit of one

One molecule can make the difference between healthy and sick tissue, but despite advances in molecular biology, tracking such minute quantities remains a challenge. Pablo Etchegoin is motivated by the prospect of early diagnosis and is using laser spectroscopy to explore the boundaries between physics and biology. Biologists can already track proteins in cells by labelling them with fluorescent dyes, but Etchegoin plans to surpass the detection limit of fluorescence spectroscopy, and any other techniques available today, by using laser spectroscopy and an effect called Raman scattering. This effect produces scattered photons, which differ in frequency from the radiation source that causes it, and is named after CV Raman, who was awarded the 1930 Nobel Prize in physics.

Nature’s builders

The search for new materials is an ongoing quest for science. Stronger, tougher, more durable and less heavy are just some of the desirable attributes scientists are looking for, and they are learning about these qualities from some of nature’s own master builders. Kate McGrath has enlisted the assistance of a tiny endemic sea urchin to investigate whether science could take more construction tips from biominerals. Biominerals are everywhere, from the patterned walls enclosing microscopic algae to the massive bones of a whale. The majority of plants and animals synthesise some form of biomineral material, and for many their survival depends on their ability to deposit the inorganic matrix quickly and efficiently.

By Veronika Meduna

Medals and awards

Alan MacDiarmid: 2000 Nobel Prize in chemistry

Paul Callaghan: FRS, FRSNZ, Rutherford Medal, PCNZM

Further reading and websites

MacDiarmid Institute for Advanced Materials and Nanotechnology website

Image courtesy MacDiarmid Institute for Advanced Materials and Nanotechnology.

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