Tag Archives: University of Cambridge

Pixels A Million Times Smaller

The smallest pixels yet created – a million times smaller than those in smartphones, made by trapping particles of light under tiny rocks of gold – could be used for new types of large-scale flexible displays, big enough to cover entire buildings. The colour pixels, developed by a team of scientists led by the University of Cambridge, are compatible with roll-to-roll fabrication on flexible plastic films, dramatically reducing their production cost.
It has been a long-held dream to mimic the colour-changing skin of octopus or squid, allowing people or objects to disappear into the natural background, but making large-area flexible display screens is still prohibitively expensive because they are constructed from highly precise multiple layers. At the centre of the pixels developed by the Cambridge scientists is a tiny particle of gold a few billionths of a metre across. The grain sits on top of a reflective surface, trapping light in the gap in between. Surrounding each grain is a thin sticky coating which changes chemically when electrically switched, causing the pixel to change colour across the spectrum.

The team of scientists, from different disciplines including physics, chemistry and manufacturing, made the pixels by coating vats of golden grains with an active polymer called polyaniline and then spraying them onto flexible mirror-coated plastic, to dramatically drive down production cost. The pixels are the smallest yet created, a million times smaller than typical smartphone pixels. They can be seen in bright sunlight and because they do not need constant power to keep their set colour, have an energy performance that makes large areas feasible and sustainable. “We started by washing them over aluminized food packets, but then found aerosol spraying is faster,” said co-lead author Hyeon-Ho Jeong from Cambridge’s Cavendish Laboratory.

These are not the normal tools of nanotechnology, but this sort of radical approach is needed to make sustainable technologies feasible,” said Professor Jeremy J Baumberg of the NanoPhotonics Centre at Cambridge’s Cavendish Laboratory, who led the research. “The strange physics of light on the nanoscale allows it to be switched, even if less than a tenth of the film is coated with our active pixels. That’s because the apparent size of each pixel for light is many times larger than their physical area when using these resonant gold architectures.”

The pixels could enable a host of new application possibilities such as building-sized display screens, architecture which can switch off solar heat load, active camouflage clothing and coatings, as well as tiny indicators for coming internet-of-things devices.

The results are reported in the journal Science Advances.

Source: https://www.cam.ac.uk/

Cancer’s ‘Internal Wiring’ Predicts Relapse Risk

The “internal wiring” of breast cancer can predict which women are more likely to survive or relapse, say researchers. The study shows that breast cancer is 11 separate diseases that each has a different risk of coming back. The hope is that the findings, in the journal Nature, could identify people needing closer monitoring and reassure others at low risk of recurrence.

Cancer Research UK said that the work was “incredibly encouraging” but was not yet ready for widespread use. The scientists, at the University of Cambridge and Stanford University, looked in incredible detail at nearly 2,000 women’s breast cancers. They went far beyond considering all breast cancers as a single disease and beyond modern medicine’s way of classifying the tumours.

Doctors currently classify breast cancers based on whether they respond to the hormone oestrogen or targeted therapies like Herceptin. The research team analysed the genetic mutations inside the tumour to create a new way of classifying them.

By following women for 20 years, they are now able to show which types of breast cancer are more likely to come back.  “This is really biology-driven, it’s the molecular wiring of your tumour, said Prof Carlos Caldas. Once and for all we need to stop talking about breast cancer as one disease, it’s a constellation of 11 diseases. “This is a very significant step to more precision-type medicine.”

Source: https://www.bbc.com/

Metallic Wood

Researchers at the School of Engineering and Applied Science, the University of Illinois at Urbana–Champaign, and the University of Cambridge have built a sheet of nickel with nanoscale pores that make it as strong as titanium, but four to five times lighter. The empty space of the pores, and the self-assembly process in which they’re made, make the porous metal akin to a natural material, such as wood. And just as the porosity of wood grain serves the biological function of transporting energy, the empty space in the researchers’ “metallic wood” could be infused with other materials. Infusing the scaffolding with anode and cathode materials would enable this metallic wood to serve double duty: a plane wing or prosthetic leg that’s also a battery. The study was led by James Pikul, assistant professor in the Department of Mechanical Engineering and Applied Mechanics at Penn Engineering.

Metallic wood foil on a plastic backing

The reason we call it metallic wood is not just its density, which is about that of wood, but its cellular nature,” Pikul says. “Cellular materials are porous; if you look at wood grain, that’s what you’re seeing—parts that are thick and dense and made to hold the structure, and parts that are porous and made to support biological functions, like transport to and from cells.

The study has been published in Nature Scientific Reports,

Source: https://penntoday.upenn.edu/

 

Electric Car: How To Make Super-Fast Charging Batteries

Researchers have identified a group of materials that could be used to make even higher power batteries. The researchers, from the University of Cambridge, used materials with a complex crystalline structure and found that lithium ions move through them at rates that far exceed those of typical electrode materials, which equates to a much faster-charging battery. Although these materials, known as niobium tungsten oxides, do not result in higher energy densities when used under typical cycling rates, they come into their own for fast charging applications. Additionally, their physical structure and chemical behaviour give researchers a valuable insight into how a safe, super-fast charging battery could be constructed, and suggest that the solution to next-generation batteries may come from unconventional materials.

Many of the technologies we use every day have been getting smaller, faster and cheaper each year – with the notable exception of batteries. Apart from the possibility of a smartphone which could be fully charged in minutes, the challenges associated with making a better battery are holding back the widespread adoption of two major clean technologies: electric cars and grid-scale storage for solar power.

We’re always looking for materials with high-rate battery performance, which would result in a much faster charge and could also deliver high power output,” said Dr Kent Griffith, a postdoctoral researcher in Cambridge’s Department of Chemistry and the paper’s first author.

In their simplest form, batteries are made of three components: a positive electrode, a negative electrode and an electrolyte. When a battery is charging, lithium ions are extracted from the positive electrode and move through the crystal structure and electrolyte to the negative electrode, where they are stored. The faster this process occurs, the faster the battery can be charged. In the search for new electrode materials, researchers normally try to make the particles smaller. “The idea is that if you make the distance the lithium ions have to travel shorter, it should give you higher rate performance,” said Griffith. “But it’s difficult to make a practical battery with nanoparticles: you get a lot more unwanted chemical reactions with the electrolyte, so the battery doesn’t last as long, plus it’s expensive to make.

Nanoparticles can be tricky to make, which is why we’re searching for materials that inherently have the properties we’re looking for even when they are used as comparatively large micron-sized particles. This means that you don’t have to go through a complicated process to make them, which keeps costs low,” explained Professor Clare Grey, also from the Department of Chemistry and the paper’s senior author. “Nanoparticles are also challenging to work with on a practical level, as they tend to be quite ‘fluffy’, so it’s difficult to pack them tightly together, which is key for a battery’s volumetric energy density.”

The results are reported in the journal Nature.

Source: https://www.cam.ac.uk/

A Pinch Of Salt Improves Drastically Battery Performance

Researchers at Queen Mary University of London, University of Cambridge and Max Planck Institute for Solid State Research have discovered how a pinch of salt can be used to drastically improve the performance of batteries. Surprisingly, the salt reacted with the sponge in special ways and turned it from a homogeneous mass to an intricate structure with fibres, struts, pillars and webs. This kind of 3D hierarchically organised carbon structure has proven very difficult to grow in a laboratory but is crucial in providing unimpeded ion transport to active sites in a battery. In the study, published in JACS (Journal of the American Chemical Society), the researchers demonstrate that the use of these materials in Lithium-ion batteries not only enables the batteries to be charged-up rapidly, but also at one of the highest capacities.

Due to their intricate architecture the researchers have termed these structures ‘nano-diatoms’, and believe they could also be used in energy storage and conversion, for example as electrocatalysts for hydrogen production.

This metamorphosis only happens when we heat the compounds to 800 degrees centigrade and was as unexpected as hatching fire-born dragons instead of getting baked eggs in the Game of Thrones. It is very satisfying that after the initial surprise, we have also discovered how to control the transformations with chemical composition,” said lead author Dr Stoyan Smoukov, from Queen Mary’s School of Engineering and Materials Science.

Source: https://www.qmul.ac.uk/