Tag Archives: Kourosh Kalantar-zadeh

Growing metallic snowflakes at the nanoscale

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Caption: Nano-scale snowflake from Gallium solvent. Credit: Waipapa Taumata Rau, University of Auckland

’tis the season for snowflakes here in the Northern Hemisphere. Oddly, these metallic snowflakes (they look more like plant leaves to me) come from the Southern Hemisphere (New Zealand and Australia to be precise). From a December 10, 2022 news item on Nanowerk, which includes a brief definition of nanotechnology written in an approachable style,

Scientists in New Zealand and Australia working at the level of atoms created something unexpected: tiny metallic snowflakes.

Why’s that significant? Because coaxing individual atoms to cooperate is leading to a revolution in engineering and technology via nanomaterials. (And creating snowflakes is cool.)

Nanoscale structures (a nanometre is one billionth of a metre) can aid electronic manufacturing, make materials stronger yet lighter, or aid environmental clean-ups by binding to toxins.

…

A December 9, 2022 University of Auckland press release (also on EurekAlert but published on December 8, 2022), which originated the news item, delves into the research,

To create metallic nanocrystals, New Zealand and Australian scientists have been experimenting with gallium, a soft, silvery metal which is used in semiconductors and, unusually, liquifies at just above room temperature. Their results were just reported in the journal Science.

…

The Australian team worked in the lab with nickel, copper, zinc, tin, platinum, bismuth, silver and aluminium, growing metal crystals in a liquid solvent of gallium. Metals were dissolved in gallium at high temperatures. Once cooled, the metallic crystals emerged while the gallium remained liquid. The New Zealand team, part of the MacDiarmid Institute for Advanced Materials and Nanotechnology, a national Centre of Research Excellence, carried out simulations of molecular dynamics to explain why differently shaped crystals emerge from different metals. (The government’s Marsden Fund supported the research.)

“What we are learning is that the structure of the liquid gallium is very important,” says Gaston. “That’s novel because we usually think of liquids as lacking structure or being only randomly structured.” Interactions between the atomistic structures of the different metals and the liquid gallium cause differently shaped crystals to emerge, the scientists showed.

The crystals included cubes, rods, hexagonal plates and the zinc snowflake shapes. The six-branched symmetry of zinc, with each atom surrounded by six neighbours at equivalent distances, accounts for the snowflake design. “In contrast to top-down approaches to forming nanostructure – by cutting away material – this bottom-up approaches relies on atoms self-assembling,” says Gaston. “This is how nature makes nanoparticles, and is both less wasteful and much more precise than top-down methods.” She says the research has opened up a new, unexplored pathway for metallic nanostructures. “There’s also something very cool in creating a metallic snowflake!”

Here’s a link to and a citation for the paper,

Liquid metal synthesis solvents for metallic crystals by Shuhada A. Idrus-Saidi, Jianbo Tang, Stephanie Lambie, Jialuo Han, Mohannad Mayyas, Mohammad B. Ghasemian, Francois-Marie Allioux, Shengxiang Cai, Pramod Koshy, Peyman Mostaghimi, Krista G. Steenbergen, Amanda S. Barnard, Torben Daeneke, Nicola Gaston, and Kourosh Kalantar-Zadeh. Science 8 Dec 2022 Vol 378, Issue 6624 pp. 1118-1124 DOI: 10.1126/science.abm2731

This paper is behind a paywall.

Revolutionizing electronics with liquid metal technology?

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I’m not sure I’d call it the next big advance in electronics, there are too many advances jockeying for that position but this work from Australia and the US is fascinating. From a Feb. 17, 2017 news item on ScienceDaily,

A new technique using liquid metals to create integrated circuits that are just atoms thick could lead to the next big advance for electronics.

The process opens the way for the production of large wafers around 1.5 nanometres in depth (a sheet of paper, by comparison, is 100,000nm thick).

Other techniques have proven unreliable in terms of quality, difficult to scale up and function only at very high temperatures — 550 degrees or more.

A Feb. 17, 2017 RMIT University press release (also on EurekAlert), which originated the news item, expands on the theme (Note: A link has been removed),

Distinguished Professor Kourosh Kalantar-zadeh, from RMIT’s School of Engineering, led the project, which also included colleagues from RMIT and researchers from CSIRO, Monash University, North Carolina State University and the University of California.

He said the electronics industry had hit a barrier.

“The fundamental technology of car engines has not progressed since 1920 and now the same is happening to electronics. Mobile phones and computers are no more powerful than five years ago.

“That is why this new 2D printing technique is so important – creating many layers of incredibly thin electronic chips on the same surface dramatically increases processing power and reduces costs.

“It will allow for the next revolution in electronics.”

Benjamin Carey, a researcher with RMIT and the CSIRO, said creating electronic wafers just atoms thick could overcome the limitations of current chip production.

It could also produce materials that were extremely bendable, paving the way for flexible electronics.

“However, none of the current technologies are able to create homogenous surfaces of atomically thin semiconductors on large surface areas that are useful for the industrial scale fabrication of chips.

“Our solution is to use the metals gallium and indium, which have a low melting point.

“These metals produce an atomically thin layer of oxide on their surface that naturally protects them. It is this thin oxide which we use in our fabrication method.

“By rolling the liquid metal, the oxide layer can be transferred on to an electronic wafer, which is then sulphurised. The surface of the wafer can be pre-treated to form individual transistors.

“We have used this novel method to create transistors and photo-detectors of very high gain and very high fabrication reliability in large scale.”

Here’s a link to and a citation for the paper,

Wafer-scale two-dimensional semiconductors from printed oxide skin of liquid metals by Benjamin J. Carey, Jian Zhen Ou, Rhiannon M. Clark, Kyle J. Berean, Ali Zavabeti, Anthony S. R. Chesman, Salvy P. Russo, Desmond W. M. Lau, Zai-Quan Xu, Qiaoliang Bao, Omid Kevehei, Brant C. Gibson, Michael D. Dickey, Richard B. Kaner, Torben Daeneke, & Kourosh Kalantar-Zadeh. Nature Communications 8, Article number: 14482 (2017) doi:10.1038/ncomms14482
Published online: 17 February 2017

This paper is open access.

Do you really want to swallow a ‘smart pill’ to measure intestinal gas or anything else?

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Caption: Smart gas sensing pills developed at RMIT University can measure intestinal gases inside the gut and send the data directly to a mobile phone. Credit: RMIT University

Caption: Smart gas sensing pills developed at RMIT University can measure intestinal gases inside the gut and send the data directly to a mobile phone.
Credit: RMIT University

Researchers at RMIT University (Australia) have tested a ‘smart pill’ (or sensor/wireless transmitter) on animals according to a Jan. 12, 2016 news item on ScienceDaily,

Researchers have conducted the first ever trials of smart pills that can measure intestinal gases inside the body, with surprising results revealing some unexpected ways that fiber affects the gut.

Intestinal gases have been linked to colon cancer, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), but their role in health is poorly understood and there is currently no easy and reliable tool for detecting them inside the gut.

The first animal trials of smart gas sensing pills developed at Australia’s RMIT University — which can send data from inside the gut directly to a mobile phone — have examined the impact of low and high-fibre diets on intestinal gases and offer new clues for the development of treatments for gut disorders.

Lead investigator Professor Kourosh Kalantar-zadeh, from the Centre for Advanced Electronics and Sensors at RMIT, said the results reversed current assumptions about the effect of fibre on the gut.

A Jan. 12, 2016 RMIT University news release on EurekAlert, which originated the news item, expands on the theme,

“We found a low-fibre diet produced four times more hydrogen in the small intestine than a high-fibre diet,” Kalantar-zadeh said.

“This was a complete surprise because hydrogen is produced through fermentation, so we naturally expected more fibre would equal more of this fermentation gas.

“The smart pills allow us to identify precisely where the gases are produced and help us understand the microbial activity in these areas – it’s the first step in demolishing the myths of food effects on our body and replacing those myths with hard facts.

“We hope this technology will in future enable researchers to design personalised diets or drugs that can efficiently target problem areas in the gut, to help the millions of people worldwide that are affected by digestive disorders and diseases.”

The trials revealed different levels of fibre in a diet affected both how much gas was produced and where it was concentrated in the gut – in the stomach, small intestine or large intestine.

The smart pills were trialled on two groups of pigs – whose digestive systems are similar to humans – fed high and low-fibre diets. The results indicate the technology could help doctors differentiate gut disorders such as IBS, showing:

  • high-fibre diets produce more methane gas in the large intestine than the low-fibre diet, suggesting that painful gut gas retention could be avoided by cutting back on high-fibre food
  • low-fibre diets produced four times more hydrogen gas in the small intestine than high-fibre, indicating a high-fibre regimen could be better for patients with IBS caused by bacterial overgrowth in small intestine
  • the ratio of carbon dioxide and methane gases remained the same in the large intestine for both diets, suggesting that neither diet would be helpful for people suffering IBS diseases associated with excess methane concentration

Here’s a link to and a citation for the paper,

Intestinal Gas Capsules: A Proof-of-Concept Demonstration by Kourosh Kalantar-zadeh, Chu K. Yao, Kyle J. Berean, Nam Ha, Jian Zhen Ou, Stephanie A. Ward, Naresh Pillai, Julian Hill, Jeremy J. Cottrell, Frank R. Dunshea, Chris McSweeney, Jane G. Muir, and  Peter R. Gibson. Gastroenterology January 2016Volume 150, Issue 1, Pages 37–39 DOI: http://dx.doi.org/10.1053/j.gastro.2015.07.072

This article appears to be open access.

Getting back to my question, will people be willing to swallow these things? The study indicates that four pigs, in total, were tested and killed afterwards. The ‘smart pill’ measurements were compared to others made with standard technologies to assure researchers the new technology was viable. This particular study seems to have served as a proof of concept rather than an in-depth analysis of intestinal gases. As to whether or not anyone will ever be asked to swallow one of these ‘smart pills’ (sensor/wireless transmitter), the scientists did not share any plans for human clinical trials. I guess one of the big questions would be, what happens to the pill (stay in your gut or expelled) once you’ve gotten your measurements?