New copper surface eliminates bacteria in just two minutes

A new surface that kills bacteria more than 100 times faster and more effectively than standard copper could help combat the growing threat of antibiotic-resistant superbugs. The new copper product is the result of a collaborative research project with RMIT University and Australia’s national science agency, CSIRO, with findings just published in Biomaterials. Copper has long been used to fight different strains of bacteria, including the commonly found golden staph, because the ions released from the metal’s surface are toxic to bacterial cells. But this process is slow when standard copper is used, as RMIT University’s Distinguished Professor Ma Qian explained, and significant efforts are underway by researchers worldwide to speed it up.

The copper magnified 500,000 times under a scanning electron microscope shows the tiny nano-scale pores in the structure

A standard copper surface will kill about 97% of golden staph within four hours,” Qian said. “Incredibly, when we placed golden staph bacteria on our specially-designed copper surface, it destroyed more than 99.99% of the cells in just two minutes.” “So not only is it more effective, it’s 120 times faster.” Importantly, said Qian, these results were achieved without the assistance of any drug. “Our copper structure has shown itself to be remarkably potent for such a common material,” he said.

The team believes there could be a huge range of applications for the new material once further developed, including antimicrobial doorhandles and other touch surfaces in schools, hospitals, homes and public transport, as well as filters in antimicrobial respirators or air ventilation systems, and in face masks. The team is now looking to investigate the enhanced copper’s effectiveness against SARS-COV-2, the virus that causes COVID-19, including assessing 3D-printed samples. Other studies suggest copper may be highly effective against the virus, leading the US Environmental Protection Agency to officially approve copper surfaces for antiviral uses earlier this year.


Could Deep Sea Mining Fuel The Electric Vehicle Boom?

The world is hungry for resources to power the green transition. As we increasingly look to solar, wind, geothermal and move towards decarbonization, consumption of minerals such as cobalt, lithium and copper, which underpin them, is set to grow markedly. One study by the World Bank estimates that to meet this demand, cobalt production will need to grow by 450% from 2018 to 2050, in pursuit of keeping global average temperature rises below 2°C. The mining of any material can give rise to complex environmental and social impacts. Cobalt, however, has attracted particular attention in recent years over concerns of unsafe working conditions and labour rights abuses associated with its production.

New battery technologies are under development with reduced or zero cobalt content, but it is not yet determined how fast and by how much these technologies and circular economy innovations can decrease overall cobalt demand. Deep-sea mining has the potential to supply cobalt and other metals free from association with such social  strife, and can reduce the raw material cost and carbon footprint of much-needed green technologies.

On the other hand, concerned scientists have highlighted our limited knowledge of the deep-sea and its ecosystems. The potential impact of mining on deep-sea biodiversitydeep-sea habitats and fisheries are still being studied, and some experts have questioned the idea that environmental impacts of mining in the deep-sea can be mitigated in the same way as those on land.

Photonic Chips

Emitting light from silicon has been the ‘Holy Grail’ in the microelectronics industry for decades. Solving this puzzle would revolutionize computing, as chips will become faster than ever. Researchers from Eindhoven University of Technology  (TU-e) now succeeded: they have developed an alloy with silicon that can emit light. The team will now start creating a silicon laser to be integrated into current chips.

Every year we use and produce significantly more data. But our current technology, based on electronic chips, is reaching its ceiling. The limiting factor is heat, resulting from the resistance that the electrons experience when traveling through the copper lines connecting the many transistors on a chip. If we want to continue transferring more and more data every year, we need a new technique that does not produce heat. Bring in photonics, which uses photons (light particles) to transfer data. In contrast to electrons, photons do not experience resistance. As they have no mass or charge, they will scatter less within the material they travel through, and therefore no heat is produced. The energy consumption will therefore be reduced. Moreover, by replacing electrical communication within a chip by optical communication, the speed of on-chip and chip-to-chip communication can be increased by a factor 1000. Data centers would benefit most, with faster data transfer and less energy usage for their cooling system. But these photonic chips will also bring new applications within reach. Think of laser-based radar for self-driving cars and chemical sensors for medical diagnosis or for measuring air and food quality.

To use light in chips, you will need a light source; an integrated laser. The main semiconductor material that computer chips are made of is silicon. But bulk silicon is extremely inefficient at emitting light, and so was long thought to play no role in photonics. Thus, scientists turned to more complex semiconductors, such as gallium arsenide and indium phosphide. These are good at emitting light but are more expensive than silicon and are hard to integrate into existing silicon microchips.

To create a silicon compatible laser, scientists needed to produce a form of silicon that can emit light. That’s exactly what researchers from Eindhoven University of Technology (TU/e) now succeeded in. Together with researchers from the universities of Jena, Linz and Munich, they combined silicon and germanium in a hexagonal structure that is able to emit light. A breakthrough after 50 years of work.

Nanowires with hexagonal silicon-germanium shells

The crux is in the nature of the so-called band gap of a semiconductor,” says lead researcher Erik Bakkers from TU/e. “If an electron ‘drops’ from the conduction band to the valence band, a semiconductor emits a photon: light.” But if the conduction band and valence band are displaced with respect to each other, which is called an indirect band gap, no photons can be emitted – as is the case in silicon. “A 50-year old theory showed however that silicon, alloyed with germanium, shaped in a hexagonal structure does have a direct band gap, and therefore potentially could emit light,” explains Bakkers.

Shaping silicon in a hexagonal structure, however, is not easy. As Bakkers and his team master the technique of growing nanowires, they were able to create hexagonal silicon in 2015. They realized pure hexagonal silicon by first growing nanowires made from another material, with a hexagonal crystal structure. Then they grew a silicon-germanium shell on this template. Elham Fadaly, shared first author of the study: “We were able to do this such that the silicon atoms are built on the hexagonal template, and by this forced the silicon atoms to grow in the hexagonal structure.” But they could not yet make them to emit light, until now. Bakkers team managed to increase the quality of the hexagonal silicon-germanium shells by reducing the number of impurities and crystal defects. When exciting the nanowire with a laser, they could measure the efficiency of the new material. Alain Dijkstra, also shared first author of the study and responsible for measuring the light emission: “Our experiments showed that the material has the right structure, and that it is free of defects. It emits light very efficiently.”

The findings have been published in the journal Nature.


Laser Method Turns Any Metal Surface Into A Bacteria Killer

Bacterial pathogens can live on surfaces for days. What if frequently touched surfaces such as doorknobs could instantly kill them offPurdue University engineers have created a laser treatment method that could potentially turn any metal surface into a rapid bacteria killer – just by giving the metal’s surface a different texture. In a study published in the journal Advanced Materials Interfaces, the researchers demonstrated that this technique allows the surface of copper to immediately kill off superbugs such as MRSA.

A laser prepares to texture the surface of copper, enhancing its antimicrobial properties

Copper has been used as an antimicrobial material for centuries. But it typically takes hours for native copper surfaces to kill off bacteria,” said Rahim Rahimi, a Purdue assistant professor of materials engineering. “We developed a one-step laser-texturing technique that effectively enhances the bacteria-killing properties of copper’s surface.”

The technique is not yet tailored to killing viruses such as the one responsible for the COVID-19 pandemic, which are much smaller than bacteria. Since publishing this work, however, Rahimi’s team has begun testing this technology on the surfaces of other metals and polymers that are used to reduce risks of bacterial growth and biofilm formation on devices such as orthopedic implants or wearable patches for chronic wounds.


How To Etch A ‘Perfect’ Solar Energy Absorber

The University of Rochester research lab that recently used lasers to create unsinkable metallic structures has now demonstrated how the same technology could be used to create highly efficient solar power generators.

In a paper in Light: Science & Applications, the lab of Chunlei Guo, professor of optics also affiliated with the Department of Physics and Astronomy and the Material Sciences Program, describes using powerful femto-second laser pulses to etch metal surfaces with nanoscale structures that selectively absorb light only at the solar wavelengths, but not elsewhere.

A regular metal surface is shiny and highly reflective. Years ago, the Guo lab developed a black metal technology that turned shiny metals pitch black.


But to make a perfect solar absorber,” Guo says, “We need more than a black metal and the result is this selective absorber.”

This surface not only enhances the energy absorption from sunlight, but also reduces heat dissipation at other wavelengths, in effect, “making a perfect metallic solar absorber for the first time,” Guo says. “We also demonstrate solar energy harnessing with a thermal electric generator device.

This will be useful for any thermal solar energy absorber or harvesting device,” particularly in  places with abundant sunlight, he adds.

The researchers experimented with aluminum, copper, steel, and tungsten, and found that tungsten, commonly used as a thermal solar absorber, had the highest solar absorption efficiency when treated with the new nanoscale structures. This improved the efficiency of thermal electrical generation by 130 percent compared to untreated tungsten.

Co-authors include Sohail Jalil, Bo Lai, Mohamed Elkabbash, Jihua Zhang, Erik M. Garcell, and Subhash Singh of the Guo lab.


Copper-based Nanomaterials Kill Cancer Cells

An interdisciplinary team of scientists from KU Leuven (Belgium), the University of Bremen (Germany), the Leibniz Institute of Materials Engineering (Germany), and the University of Ioannina (Greece) has succeeded in killing tumour cells in mice using nano-sized copper compounds together with immunotherapy. After the therapy, the cancer did not return.

Recent advances in cancer therapy use one’s own immunity to fight the cancer. However, in some cases, immunotherapy has proven unsuccessful. The team of biomedical researchers, physicists, and chemical engineers found that tumours are sensitive to copper oxide nanoparticles – a compound composed of copper and oxygen. Once inside a living organism, these nanoparticles dissolve and become toxic. By creating the nanoparticles using iron oxide, the researchers were able to control this process to eliminate cancer cells, while healthy cells were not affected.

Any material that you create at a nanoscale has slightly different characteristics than its normal-sized counterpart,” explain Professor Stefaan Soenen and Dr Bella B. Manshian from the Department of Imaging and Pathology, who worked together on the study. “If we would ingest metal oxides in large quantities, they can be dangerous, but at a nanoscale and at controlled, safe, concentrations, they can actually be beneficial.

As the researchers expected, the cancer returned after treating with only the nanoparticles. Therefore, they combined the nanoparticles with immunotherapy. “We noticed that the copper compounds not only could kill the tumour cells directly, they also could assist those cells in the immune system that fight foreign substances, like tumours,” says Dr Manshian.

The combination of the nanoparticles and immunotherapy made the tumours disappear entirely and, as a result, works as a vaccine for lung and colon cancer – the two types that were investigated in the study. To confirm their finding, the researchers injected tumour cells back into the mice. These cells were immediately eliminated by the immune system, which was on the lookout for any new, similar, cells invading the body.


How To Make Solar Panels More Sustainable And Cheaper

An innovative way to pattern metals has been discovered by scientists in the Department of Chemistry at the University of Warwick in UK, which could make the next generation of  solar panels more sustainable and cheaperSilver and copper are the most widely used electrical conductors in modern electronics and solar cells. However, conventional methods of patterning these metals to make the desired pattern of conducting lines are based on selectively removing metal from a film by etching using harmful chemicals or printing from costly metal inks.

Scientists from the Department of Chemistry at the University of Warwick, have developed a way of patterning these metals that is likely to prove much more sustainable and cheaper for large scale production, because there is no metal waste or use of toxic chemicals, and the fabrication method is compatible with continuous roll-to-roll processing. Dr Ross Hatton and Dr Silvia Varagnolo have discovered that silver and copper do not condense onto extremely thin films of certain highly fluorinated organic compounds when the metal is deposited by simple thermal evaporation.

Thermal evaporation is already widely used on a large scale to make the thin metal film on the inside of crisp packets, and organofluorine compounds are already common place as the basis of non-stick cooking pans. The researchers have shown that the organofluorine layer need only be 10 billionths of a metre thick to be effective, and so only tiny amounts are needed. This unconventional approach also leaves the metal surface uncontaminated, which Hatton believes will be particularly important for the next generation sensors, which often require uncontaminated patterned films of these metals as platforms onto which sensing molecules can be attached.

To help address the challenges posed by climate change, there is a need for colour tuneable, flexible and light weight solar cells that can be produced at low cost, particularly for applications where conventional rigid silicon solar cells are unsuitable such as in electric cars and semi-transparent solar cells for buildings. Solar cells based on thin films of organic, perovskite or nano-crystal semiconductors all have potential to meet this need, although they all require a low cost, flexible transparent electrode. Hatton and his team have used their method to fabricate semi-transparent organic solar cells in which the top silver electrode is patterned with millions of tiny apertures per square centimetre, which cannot be achieved by any other scalable means directly on top of an organic electronic device.

This innovation enables us to realise the dream of truly flexible, transparent electrodes matched to needs of the emerging generation of thin film solar cells, as well as having numerous other potential applications ranging from sensors to low-emissivity glass” explains Dr Hatton from the Department of Chemistry at the University of Warwick.

The work is published in the journal Materials Horizons.


The Sea Floor Is Full Of Minerals Vital in The Manufacture Of Smartphones

From the safety of their research vessel, scientists are exploring one of Earth’s last frontiers – the sea floor – to discover more about valuable minerals vital in the manufacture of smartphones. The researchers, from the University of Bergen in Norway, are sending robots 2,500m down into the waters between Norway and Greenland, to try to understand the environments potentially rich with rare earth minerals.


The ocean sea floor on Earth is, for the most part, unknown,” scientist Thibaut Barreyre said. “It’s totally fair to say that we know much more about the surface of the moon and Mars – mapped by satellites and different devices – than we know about our own planet.”

The international team is using technology including autonomous robots and human-piloted submarines to explore the sea’s dark depths where zinc, gold and copper are also found. The scientists hope the explorations will reveal why some areas have minerals and others do not, how much is down there and what damage mining them would have on the environment. A viable new source of rare earths, a group of 17 elements used in the production of smartphone screens, magnets, camera lenses and X-ray machines could be highly lucrative. But it is not that simple, Barreyre explained. “Some of them (waters) are rich in gold, copper, zinc and rare earths. And others have almost none of those. And that’s why it’s very important to us as scientists to understand it,”he commented. The team, which began exploring the area last year, will spend the next five years searching.