Posts belonging to Category AFM

Swiches For Electricity: Atomic-Scale Manufacturing

Robert Wolkow is no stranger to mastering the ultra-small and the ultra-fast. A pioneer in atomic-scale science with a Guinness World Record to boot (for a needle with a single atom at the point), Wolkow’s team, together with collaborators at the Max Planck Institute in Hamburg, have just released findings that detail how to create atomic switches for electricity, many times smaller than what is currently used. With applications for practical systems like silicon semi-conductor electronics, it means smaller, more efficient, more energy-conserving nanocomputers, as just one example of the technology revolution that is unfolding right before our very eyes (if you can squint that hard).


It’s something you don’t even hear about yet, but atom-scale manufacturing is going to be world-changing. This is just the beginning of what will be at least a century of developments in atom-scale manufacturing, and it will be transformational“.  “This is the first time anyone’s seen a switching of a single-atom channel,” explains Wolkow, a physics professor at the University of Alberta and the Principal Research Officer at Canada’s National Institute for Nanotechnology. “You’ve heard of a transistor—a switch for electricity—well, our switches are almost a hundred times smaller than the smallest on the market today.

Today’s tiniest transistors operate at the 14 nanometer level, which still represents thousands of atoms. Wolkow’s and his team at the University of Alberta, NINT, and his spinoff QSi, have worked the technology down to just a few atoms. Since computers are simply a composition of many on/off switches, the findings point the way not only to ultra-efficient general purpose computing but also to a new path to quantum computing.


Solar Cells: How To Boost Perovkite Efficiency Up To 31%

Scientists from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a possible secret to dramatically boosting the efficiency of perovskite solar cells hidden in the nanoscale peaks and valleys of the crystalline material.

Solar cells made from compounds that have the crystal structure of the mineral perovskite have captured scientists’ imaginations. They’re inexpensive and easy to fabricate, like organic solar cells. Even more intriguing, the efficiency at which perovskite solar cells convert photons to electricity has increased more rapidly than any other material to date, starting at three percent in 2009—when researchers first began exploring the material’s photovoltaic capabilities—to 22 percent today. This is in the ballpark of the efficiency of silicon solar cells.

Now, as reported online July 4 in the journal Nature Energy, a team of scientists from the Molecular Foundry and the Joint Center for Artificial Photosynthesis, both at Berkeley Lab, found a surprising characteristic of a perovskite solar cell that could be exploited for even higher efficiencies, possibly up to 31 percent.

Using photoconductive atomic force microscopy, the scientists mapped two properties on the active layer of the solar cell that relate to its photovoltaic efficiency. The maps revealed a bumpy surface composed of grains about 200 nanometers in length, and each grain has multi-angled facets like the faces of a gemstone. Unexpectedly, the scientists discovered a huge difference in energy conversion efficiency between facets on individual grains. They found poorly performing facets adjacent to highly efficient facets, with some facets approaching the material’s theoretical energy conversion limit of 31 percent. The scientists say these top-performing facets could hold the secret to highly efficient solar cells, although more research is needed.

perovskite solar panel

“If the material can be synthesized so that only very efficient facets develop, then we could see a big jump in the efficiency of perovskite solar cells, possibly approaching 31 percent,” says Sibel Leblebici, a postdoctoral researcher at the Molecular Foundry.

Leblebici works in the lab of Alexander Weber-Bargioni, who is a corresponding author of the paper that describes this research. Ian Sharp, also a corresponding author, is a Berkeley Lab scientist at the Joint Center for Artificial Photosynthesis. Other Berkeley Lab scientists who contributed include Linn Leppert, Francesca Toma, and Jeff Neaton, the director of the Molecular Foundry.


Nanoscope Sees Images 100,000 Times Smaller Than A Human Hair

A microscope that produces images a hundred-thousand times smaller than the width of a human hair wasn’t quite enough for Dr David Dowsett. At the Luxembourg Institute of Science and Technology (LIST), Dowsett and his team added a specially designed prototype spectrometer. They say their secondary ion mass spectrometer – or SIMS – analysis tool, is one of the most powerful in the world.

nanoscope list

A human hair is about 50 to 100 microns in diameter. The resolution of our microscope images is half a nanometer and the resolution of our SIMS images is about 10 nanometres. So, that’s about 100,000 times smaller than the diameter of a human hair“, says Dr. David Dowsett, Senior research & Technology Associate at the  Luxembourg Institute of  Science and  Technology (LIST). And it’s attracting interest from big business for it’s immense imaging and chemical mapping capabilities… including from cosmetic companies.  “So when they say ‘this is the science bit’ – that’s actually us. We’ve worked for a least one of the big pharmaceutical companies developing shampoo, so looking at whether the shampoo really penetrates into the hair,” he adds.
The precision tool’s impact could be huge for many industries, including the development of new semiconductors and Lithium ion batteries. It could also play a vital role in the the improvement and development of medicine.
We can follow where those nanoparticles have been uptaken into, for example, human cells. And also we can see whether or not a labelled drug is present within the cell, in the same place as the nanoparticle; so we can really start to test whether a delivery system is effective“, concludes Dowsett. Now he is working with his team on an improved version of the device and investigating possibilities to commercialise the development.


Nanoprobe Lightens Up Tumors

Researchers from A*STAR (Singapore) have developed a hybrid metal––polymer nanoparticle that lights up in the acidic environment surrounding tumor cells. Nonspecific probes that can identify any kind of tumor are extremely useful for monitoring the location and spread of cancer and the effects of treatment, as well as aiding initial diagnosis.

Cancerous tumors typically have lower than normal pH levels, which correspond to increased acidity both inside the cells and within the extracellular microenvironment surrounding the cells. This simple difference between tumor cells and normal cells has led several research groups to develop probes that can detect the low pH of tumors using optical imaging, magnetic resonance and positron emission tomography.

Most of these probes, however, target the intracellular pH, which requires the probes to enter the cells in order to work. A greater challenge has been to detect the difference in extracellular pH between healthy tissue and tumor tissue as the pH difference is smaller. Success would mean that the probes are not required to enter the cells.

nanoprobe lightens up tumors
Intravenous administration of a hybrid metal–polymer nanoprobe causes tumor tissue to fluoresce

Our aim is to address the challenge of illuminating tumors universally,” says Bin Liu from the A*STAR Institute of Materials Research and Engineering. Liu’s team, together with colleagues from the National University of Singapore, based their new probe on polymers that self-assemble on gold nanoparticles.

Nano Pixels To Produce Synthetic Retinas

A new discovery will make it possible to create pixels just a few hundred nanometres across that could pave the way for extremely high-resolution and low-energy thin, flexible displays for applications such as ‘smartglasses, synthetic retinas, and foldable screens. A team led by Oxford University scientists explored the link between the electrical and optical properties of phase change materials (materials that can change from an amorphous to a crystalline state). They found that by sandwiching a seven nanometre thick layer of a phase change material (GST) between two layers of a transparent electrode they could use a tiny current to ‘draw’ images within the sandwich ‘stack’.

Initially still images were created using an atomic force microscope but the team went on to demonstrate that such tiny ‘stacks‘ can be turned into prototype pixel-like devices. These ‘nano-pixels‘ – just 300 by 300 nanometres in size – can be electrically switchedon and offat will, creating the coloured dots that would form the building blocks of an extremely high-resolution display technology.

nano pix imageStill images drawn with the technology: at around 70 micrometres across each image is smaller than the width of a human hair.

Whilst the work is still in its early stages, realising its potential, the Oxford team has filed a patent on the discovery with the help of Isis Innovation, Oxford University‘s technology commercialisation company. Isis is now discussing the displays with companies who are interested in assessing the technology, and with investors.

A report of the research is published in this week’s Nature.