Practical applications at one-millionth of a millimetre

Materials research conducted by the Nano and Molecular Systems Research Unit has led to a patented innovation, which enhances energy efficiency. Operating on a nano-scale also seems to play a critical role in climate change. One of the Research Unit's key research methods--synchrotron radiation (SR)--has been used in multiple scientific fields, ranging from medicine to history. 

"Nanoparticles are everywhere," says Professor Marko Huttula, gesturing toward the white wall in his workroom. It gets its colour from the titanium oxide particles in the paint, whose size is measured in nanometres, which is one-millionth of a millimetre.

Headed by Professor Marko Huttula, the Nano and Molecular Systems Research Unit explores the physics of nanomaterials and their manipulation at the molecular level. Some of the research instruments used by the unit are proprietary, such as the  magnetic bottle spectrometer. Photo by Juha Sarkkinen.

Although nature is teeming with nano-sized particles, more and more of them are human-made, whether in the form of microchips or air pollution.

"The world is heading toward nano, which cannot be understood with macroscopic models. At that size, quantum mechanics begins to run the show: properties can change very quickly as size decreases," explains Huttula.

"We start at the atomic scale and make an effort to understand nanomaterials."

 

Biomimicing nanosurface helps photocells absorb more light

 

The "we" refers to University of Oulu's Nano and Molecular Systems Research Unit, which is a team of some 45 researchers headed by Huttula. The unit's research is focused on functional nanomaterials, practical applications, whose function is based on nano-scale structures.

One of the most high-profile results of the research is a patented innovation and the company established for its commercialisation: WMZ-NanoSurfaces. The innovation is a nano-surface designed to enhance light collection. The nano-surface is based on "biomimicry", which involves solutions designed to emulate natural functions and processes.

"Thanks to evolution, plants are optimised to absorb solar radiation. We're just copying the surface structure of different plant leaves and applying it to a polymer surface," describes Huttula.

Surface structure of leaves.

"When this kind of polymer film is placed on a photocell, light collection is enhanced as much as 17 per cent. There is no increase in the mount of energy, but there is less reflective loss."

The Research Unit published its findings at the beginning of 2015 - the first in the world to do so. The mimicry subjects were, among others, the leaves of lotus and bamboo plants.  At this stage, the method is direct copying, but the aim is to eventually determine whether the combination of natural models would outperform evolutionary outcomes.

Designed to be applied on top of solar cells, the film enhances the generation of solar power, but it can also be used on greenhouses. Increasing the percentage of solar power serves both sustainable development and consumers, as the growing of winter produce would require less purchased heat.

Biomimicry also makes the nano-surface water-repellent and self-cleaning. And films for photocells and greenhouse panels are not the only planned applications: a surface structure has already been copied directly to a glass surface and silicon.  "The manufacturing technique itself can be updated," says Huttula.

Another biomimicry application is structural colouration, which is a method that has been understood for centuries. In structural colouration, the desired colour is created using the reflective properties of a surface structure, not an actual pigment. This is the same principle as found in, for example, a butterfly wing, which might appear blue even though the wing itself contains no pigment reflecting light at a blue wavelength.

 

Nanoparticles behave unpredictably in the atmosphere

 

Another area where the Research Unit excels is atmospheric nanoparticles. They affect, for example, climate change, the ozone layer and health.

"Until recently, it was always assumed that they were a homogeneous mass, but this isn't the case at all. The behaviour of nanoparticles varies, and their incidence is the single biggest uncertainty factor in climate models. For example, carbon nanoparticles can have either a warming or cooling effect," explains Huttula.

With regard to health, dissertation research conducted in co-operation with the North Ostrobothnia Hospital District examines nanoparticles in health care.

Research conducted by the unit is largely applied.

"Together with the University of Oulu Process Metallurgy Group, we are developing steel mill control methods.  Measuring spectra allows us to see what atoms are there, at what temperature and in what molecular environment. This method is being used in the commercialisation of spinoff enterprise Luxmet.”

Spectral analysis, or spectroscopy, is a key tool used by the Nano and Molecular Systems Research Unit. An even more important role is played by synchrotron radiation (SR), i.e. the electromagnetic radiation generated in a synchrotron, which is similar to a particle accelerator.

Synchrotron radiation ranges from low energy infrared radiation to visible light and high-energy x-ray radiation. However, as a research method, its versatility, sensitivity and resolution is far superior to, for example infrared or x-ray imaging.

"With the push of a button, we can choose the energy level and other properties of the synchrotron radiation. In addition to this, it can be aimed forward in an extremely small beam, thus making it easy to target a nano-sized area."

 "Radiation is produced by excited electrons, which deviate from their path. The electron radiates in all directions, but at the speed of light the theory of relativity kicks in and, from the observer's point of view, the radiation moves forward in a very tiny beam."

 

Synchrotron radiation used in multidisciplinary research

 

Synchrotron radiation can be characterised as a basic research method: it is used in, for example, medicine, biology, chemistry, environmental sciences, archaeology and history research.

"It was used to reveal the Archimedes Palimpsest, which had been overwritten with a Christian prayerbook. University of Oulu Associate Professor Simo Saarakkala is using it to study osteoporosis, and we have used it for measuring samples from Natural Resources Institute Finland," says Huttula.

The Nano and Molecular Systems Research Unit conducts most of its experiments at the MAX IV Laboratory in Lund, Sweden. The University of Oulu is co-ordinating Finland's participation in the MAX IV synchrotron, which is currently under construction.

"The Colosseum would fit inside it. Something like this really should be done with international co-operation." 

Researchers can use the 'supermicroscope' of the MAX IV Laboratory in Lund, Sweden in nanomaterials research.  Synchrotron radiation is a key research method for nanoparticles.

 

Text: Jarno Mällinen

Last updated: 22.12.2016