Tag Archives: KAUST

Putting a gold atom in a silver nanocluster changes things

Considering that the King Abdullah University of Science and Technology (KAUST) opened on Sept. 23, 2009 (mentioned in my Sept. 24, 2009 post; scroll down about 50% of the way), the university has done a remarkable job of establishing itself within the research community. Here’s some of the latest news from KAUST in a July 15, 2016 news item on Nanowerk,

The appearance of metals, such as their shiny surface or their electrical conductivity, is determined by the ensemble of atoms that comprise the metal. The situation differs on the molecular scale, and KAUST researchers have shown that replacing a single atom in a cluster of 25 silver atoms with one gold atom fundamentally changes its properties …

Composing a silver nanocrystal: the center silver atom (a) surrounded by a cage of 12 other silver atoms (b) embedded by further atoms (c) and stabilized by further ligands (d). Reproduced with permission from ref 1.© 2016 John Wiley and Sons.

Composing a silver nanocrystal: the center silver atom (a) surrounded by a cage of 12 other silver atoms (b) embedded by further atoms (c) and stabilized by further ligands (d). Reproduced with permission from ref 1.© 2016 John Wiley and Sons.

A July (??), 2016 KAUST news release, which originated the news item, provides more detail,

Metal atom nanoclusters are made from a core of a few metal atoms surrounded by a protective shell of stabilizing ligands. Nanoclusters come in different sizes, but each stable variation of nanoclusters has exactly the same number of metal atoms. This leads to very controllable properties, noted Osman Bakr, KAUST associate professor of material science and engineering and leader of the research team.

“Nanoclusters have unique arrangements of atoms and size-dependent absorption, fluorescence, electronic and catalytic properties,” he said.

A popular metal nanocluster is [Ag25(SR)18], which consists of of 25 silver atoms. This nanocluster is unique as it corresponds to a gold nanocluster that has exactly the same number of atoms. Both clusters have different properties due to the different metal used. To understand how exactly the atomic composition affects these properties, the researchers replaced a single silver atom with gold.

Replacing a single atom in a nanocluster is a difficult task. Direct chemical methods can be used, but these give little control over how many atoms are replaced, making it difficult to ascribe particular properties to the nanocluster structure.

Instead, the researchers used a galvanic replacement process that relies on difference in the electrochemical potential between the incoming and outgoing atoms to induce atomic replacements. To their surprise, the process produced a reliable and precise atomic exchange in which only the center silver atom is replaced by gold.

The replacement yielded dramatic changes in the nanocluster. A solution of the silver nanoclusters appears orange, whereas after the replacement of the central atom the color turns dark green.

This indicates more fundamental changes in properties, Bakr said. “The ambient stability and fluorescence of the nanocluster were enhanced by a factor of 25 as a result of this single atom replacement. Furthermore, we are now able to demonstrate the importance of a single atom impurity on nanoparticles and modulate the properties at the single atom level,” he noted.

The reliable replacement of only a single gold atom opens the door to a more systematic investigation of metal nanoclusters, which can help to uncover the mechanisms of the chemical and physical changes arising from the replacement.

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

Templated Atom-Precise Galvanic Synthesis and Structure Elucidation of a [Ag24Au(SR)18] Nanocluster by Dr. Megalamane S. Bootharaju, Chakra P. Joshi, Dr. Manas R. Parida, Prof. Omar F. Mohammed and Prof. Osman M. Bakr. Angewandte Chemie International Edition DOI: 10.1002/anie.201509381 Version of Record online: 27 NOV 2015

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

They’ve certainly waited a while to tout this research. Ah well. This paper is behind a paywall.

Biohackers (also known as bodyhackers or grinders) become more common?

Stephen Melendez’s June 11, 2016 story about biohackers/bodyhackers/grinders for Fast Company sports a striking image in the banner, an x-ray of a pair hands featuring some mysterious additions to the webbing between thumbs and forefingers (Note: Links have been removed),

Tim Shank can guarantee he’ll never leave home without his keys. Why? His house keys are located inside his body.

Shank, the president of the Minneapolis futurist group TwinCities+, has a chip installed in his hand that can communicate electronically with his front door and tell it to unlock itself. His wife has one, too.

In fact, Shank has several chips in his hand, including a near field communication (NFC) chip like the ones used in Apple Pay and similar systems, which stores a virtual business card with contact information for TwinCities+. “[For] people with Android phones, I can just tap their phone with my hand, right over the chip, and it will send that information to their phone,” he says. In the past, he’s also used a chip to store a bitcoin wallet.

Shank is one of a growing number of “biohackers” who implant hardware ranging from microchips to magnets inside their bodies.

Certainly the practice seems considerably more developed since the first time it was mentioned here in a May 27, 2010 posting about a researcher who’d implanted a chip into his body which he then contaminated with a computer virus. In the comments, you’ll find Amal Grafstraa who’s mentioned in the Melendez article at some length, from the Melendez article (Note: Links have been removed),

Some biohackers use their implants in experimental art projects. Others who have disabilities or medical conditions use them to improve their quality of life, while still others use the chips to extend the limits of human perception. …

Experts sometimes caution that the long-term health risks of the practice are still unknown. But many biohackers claim that, if done right, implants can be no more dangerous than getting a piercing or tattoo. In fact, professional body piercers are frequently the ones tasked with installing these implants, given that they possess the training and sterilization equipment necessary to break people’s skin safely.

“When you talk about things like risk, things like putting it in your body, the reality is the risk of having one of these installed is extremely low—it’s even lower than an ear piercing,” claims Amal Graafstra, the founder of Dangerous Things, a biohacking supply company.

Graafstra, who is also the author of the book RFID Toys, says he first had an RFID chip installed in his hand in 2005, which allowed him to unlock doors without a key. When the maker movement took off a few years later, and as more hackers began to explore what they could put inside their bodies, he founded Dangerous Things with the aim of ensuring these procedures were done safely.

“I decided maybe it’s time to wrap a business model around this and make sure that the things people are trying to put in their bodies are safe,” he says. The company works with a network of trained body piercers and offers online manuals and videos for piercers looking to get up to speed on the biohacking movement.

At present, these chips are capable of verifying users’ identities and opening doors. And according to Graafstra, a next-generation chip will have enough on-board cryptographic power to potentially work with credit card terminals securely.

“The technology is there—we can definitely talk to payment terminals with it—but we don’t have the agreements in place with banks [and companies like] MasterCard to make that happen,” he says.

Paying for goods with an implantable chip might sound unusual for consumers and risky for banks, but Graafstra thinks the practice will one day become commonplace. He points to a survey released by Visa last year that found that 25% of Australians are “at least slightly interested” in paying for purchases through a chip implanted in their bodies.

Melendez’s article is fascinating and well worth reading in its entirety. It’s not all keys and commerce as this next and last excerpt shows,

Other implantable technology has more of an aesthetic focus: Pittsburgh biohacking company Grindhouse Wetware offers a below-the-skin, star-shaped array of LED lights called Northstar. While the product was inspired by the on-board lamps of a device called Circadia that Grindhouse founder Tim Cannon implanted to send his body temperature to a smartphone, the commercially available Northstar features only the lights and is designed to resemble natural bioluminescence.

“This particular device is mainly aesthetic,” says Grindhouse spokesman Ryan O’Shea. “It can backlight tattoos or be used in any kind of interpretive dance, or artists can use it in various ways.”

The lights activate in the presence of a magnetic field—one that is often provided by magnets already implanted in the same user’s fingertips. Which brings up another increasingly common piece of bio-hardware: magnetic finger implants. ….

There are other objects that can be implanted in bodies. In one case, an artist, Wafaa Bilal had a camera implanted into the back of his head for a 3rd eye. I mentioned the Iraqi artist in my April 13, 2011 posting titled: Blood, memristors, cyborgs plus brain-controlled computers, prosthetics, and art (scroll down about 75% of the way). Bilal was unable to find a doctor who would perform the procedure so he went to a body-piercing studio. Unfortunately, the posting chronicles his infection and subsequent removal of the camera (h/t Feb. 11, 2011 BBC [British Broadcasting Corporation] news online article).


It’s been a while since I’ve written about bodyhacking and I’d almost forgotten about the practice relegating it to the category of “one of those trendy ideas that get left behind as interest shifts.” My own interest had shifted more firmly to neuroprosthetics (the integration of prostheses into the nervous system).

I had coined a tag for bodyhacking and neuroprostheses: machine/flesh which covers both those topics and more (e.g. cyborgs) as we continue to integrate machines into our bodies.

Final note

I was reminded of Wafaa Bilal recently when checking out a local arts magazine, Preview: the gallery guide, June/July/August 2016 issue. His work (the 168:01show) is being shown in Calgary, Alberta, Canada at the Esker Foundation from May 27 to August 28, 2016,

168:01 is a major solo exhibition of new and recent work by Iraqi-born, New York-based artist Wafaa Bilal, renowned for his online performances and technologically driven encounters that speak to the impact of international politics on individual lives.

In 168:01, Bilal takes the Bayt al-Hikma, or House of Wisdom, as a starting point for a sculptural installation of a library. The Bayt al-Hikma was a major academic center during the Islamic Golden Age where Muslim, Jewish, and Christian scholars studied the humanities and science. By the middle of the Ninth Century, the House of Wisdom had accumulated the largest library in the world. Four centuries later, a Mongol siege laid waste to all the libraries of Baghdad along with the House of Wisdom. According to some accounts, the library was thrown into the Tigris River to create a bridge of books for the Mongol army to cross. The pages bled ink into the river for seven days – or 168 hours, after which the books were drained of knowledge. Today, the Bayt al-Hikma represents one of the most well-known examples of historic cultural loss as a casualty of wartime.

For this exhibition, Bilal has constructed a makeshift library filled with empty white books. The white books symbolize the priceless cultural heritage destroyed at Bayt al-Hikma as well as the libraries, archives, and museums whose systematic decimation by occupying forces continues to ravage his homeland. Throughout the duration of the exhibition, the white books will slowly be replaced with visitor donations from a wishlist compiled by The College of Fine Arts at the University of Baghdad, whose library was looted and destroyed in 2003. At the end of each week a volunteer unpacks the accumulated shipments, catalogues each new book by hand, and places the books on the shelves. At the end of the exhibition, all the donated books will be sent to the University of Baghdad to help rebuild their library. This exchange symbolizes the power of individuals to rectify violence inflicted on cultural spaces that are meant to preserve and store knowledge for future generations.

In conjunction with the library, Bilal presents a powerful suite of photographs titled The Ashes Series that brings the viewer closer to images of violence and war in the Middle East. In an effort to foster empathy and humanize the onslaught of violent images that inundate Western media during wartime, Bilal has reconstructed journalistic images of the destruction caused by the Iraq War. He writes, “Reconstructing the destructed spaces is a way to exist in them, to share them with an audience, and to provide a layer of distance, as the original photographs are too violent and run the risk of alienating the viewer. It represents an attempt to make sense of the destruction and to preserve the moment of serenity after the dust has settled, to give the ephemeral moment extended life in a mix of beauty and violence.” In the photograph Al-Mutanabbi Street from The Ashes Series, the viewer encounters dilapidated historic and modern buildings on a street covered with layers upon layers of rubble and fragments of torn books. Bilal’s images emanate a slowness that deepens engagement between the viewer and the image, thereby inviting them to share the burden of obliterated societies and reimagine a world built on the values of peace and hope.

The House of Wisdom has been mentioned here a few times perhaps most comprehensively and in the context of the then recent opening of the King Abdullah University for Science and Technology (KAUST; located in Saudi Arabia) in this Sept. 24, 2009 posting (scroll down about 45% of the way).

Anyone interested in hacking their own body?


I expect you can find out more Amal Grafstraa’s website.

King Abdullah University of Science and Technology (Saudi Arabia) develops sensors from household materials

Researchers at the King Adbullah University of Science and Technology (KAUST) are developing sensors made of household materials according to a Feb. 19, 2016 KAUST news release (also on EurekAlert but dated Feb. 21, 2016),

Everyday materials from the kitchen drawer, such as aluminum foil, sticky note paper, sponges and tape, have been used by a team of electrical engineers from KAUST to develop a low-cost sensor that can detect external stimuli, including touch, pressure, temperature, acidity and humidity.

The sensor, which is called Paper Skin, performs as well as other artificial skin applications currently being developed while integrating multiple functions using cost-effective materials1.

“This work has the potential to revolutionize the electronics industry and opens the door to commercializing affordable high-performance sensing devices,” stated Muhammad Mustafa Hussain from the University’s Integrated Nanotechnology Lab, where the research was conducted.

Wearable and flexible electronics show promise for a variety of applications, such as wireless monitoring of patient health and touch-free computer interfaces. Current research in this direction employs expensive and sophisticated materials and processes.

The team used sticky note paper to detect humidity, sponges and wipes to detect pressure and aluminum foil to detect motion. Coloring a sticky note with an HB pencil allowed the paper to detect acidity levels, and aluminum foil and conductive silver ink were used to detect temperature differences.

The materials were put together into a simple paper-based platform that was then connected to a device that detected changes in electrical conductivity according to external stimuli.

Increasing levels of humidity, for example, increased the platform’s ability to store an electrical charge, or its capacitance. Exposing the sensor to an acidic solution increased its resistance, while exposing it to an alkaline solution decreased it. Voltage changes were detected with temperature changes. Bringing a finger closer to the platform disturbed its electromagnetic field, decreasing its capacitance.

The team leveraged the various properties of the materials they used, including their porosity, adsorption, elasticity and dimensions to develop the low-cost sensory platform. They also demonstrated that a single integrated platform could simultaneously detect multiple stimuli in real time.

Several challenges must be overcome before a fully autonomous, flexible and multifunctional sensory platform becomes commercially achievable, explained Hussain. Wireless interaction with the paper skin needs to be developed. Reliability tests also need to be conducted to assess how long the sensor can last and how good its performance is under severe bending conditions.

“The next stage will be to optimize the sensor’s integration on this platform for applications in medical monitoring systems. The flexible and conformal sensory platform will enable simultaneous real-time monitoring of body vital signs, such as heart rate, blood pressure, breathing patterns and movement,” Hussain said.

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

Paper Skin Multisensory Platform for Simultaneous Environmental Monitoring by Joanna M. Nassar, Marlon D. Cordero, Arwa T. Kutbee, Muhammad A. Karimi, Galo A. Torres Sevilla, Aftab M. Hussain, Atif Shamim, and Muhammad M. Hussain. Advanced Materials Technologies DOI: 10.1002/admt.201600004 Article first published online: 19 FEB 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This appears to be an open access paper.

Nano-alchemy: silver nanoparticles that look like and act like gold

This work on ‘nano-alchemy’ comes out of the King Abduhllah University of Science and Technology (KAUST) according to a Sept. 22, 2015 article by Lisa Zynga for phys.org (Note: A link has been removed),

In an act of “nano-alchemy,” scientists have synthesized a silver (Ag) nanocluster that is virtually identical to a gold (Au) nanocluster. On the outside, the silver nanocluster has a golden yellow color, and on the inside, its chemical structure and properties also closely mimic those of its gold counterpart. The work shows that it may be possible to create silver nanoparticles that look and behave like gold despite underlying differences between the two elements, and could lead to creating similar analogues between other pairs of elements.

“In some aspects, this is very similar to alchemy, but we call it ‘nano-alchemy,'” Bakr [Osman Bakr, Associate Professor of Materials Science and Engineering at King Abdullah University of Science and Technology (KAUST) in Saudi Arabia] told Phys.org. “When we first encountered the optical spectrum of the silver nanocluster, we thought that we may have inadvertently switched the chemical reagents for silver with gold, and ended up with gold nanoparticles instead. But repeated synthesis and measurements proved that the clusters were indeed silver and yet show properties akin to gold. It was really surprising to us as scientists to find not only similarities in the color and optical properties, but also the X-ray structure.”

In their study, the researchers performed tests demonstrating that the silver and gold nanoclusters have very similar optical properties. Typically, silver nanoclusters are brown or red in color, but this one looks just like gold because it emits light at almost the same wavelength (around 675 nm) as gold. The golden color can be explained by the fact that both nanoclusters have virtually identical crystal structures.

The question naturally arises: why are these silver and gold nanoclusters so similar, when individual atoms of silver and gold are very different, in terms of their optical and structural properties? As Bakr explained, the answer may have to do with the fact that, although larger in size, the nanoclusters behave like “superatoms” in the sense that their electrons orbit the entire nanocluster as if it were a single giant atom. These superatomic orbitals in the silver and gold nanoclusters are very similar, and, in general, an atom’s electron configuration contributes significantly to its properties.

Here’s one of the images used to illustrate Zynga’s article and the paper published by the American Chemical Society,

(Left) Optical properties of the silver and gold nanoclusters, with the inset showing photographs of the actual color of the synthesized nanoclusters. The graph shows the absorption (solid lines) and normalized emission (dotted lines) spectra. (Right) Various representations of the X-ray structure of the silver nanocluster. Credit: Joshi, et al. ©2015 American Chemical Society

(Left) Optical properties of the silver and gold nanoclusters, with the inset showing photographs of the actual color of the synthesized nanoclusters. The graph shows the absorption (solid lines) and normalized emission (dotted lines) spectra. (Right) Various representations of the X-ray structure of the silver nanocluster. Credit: Joshi, et al. ©2015 American Chemical Society

I encourage you to read Zynga’s article in its entirety. For the more technically inclined, here’s a link to and a citation for the researchers’ paper,

[Ag25(SR)18]: The “Golden” Silver Nanoparticle by Chakra P. Joshi, Megalamane S. Bootharaju, Mohammad J. Alhilaly, and Osman M. Bakr.J. Am. Chem. Soc., 2015, 137 (36), pp 11578–11581 DOI: 10.1021/jacs.5b07088 Publication Date (Web): August 31, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Spray-on solar cells from the University of Toronto (Canada)

It’s been a while since there’s been a solar cell story from the University of Toronto (U of T) and I was starting to wonder if Ted (Edward) Sargent had moved to another educational institution. The drought has ended with the announcement of three research papers being published by researchers from Sargent’s U of T laboratory. From a Dec. 5, 2014 ScienceDaily news item,

Pretty soon, powering your tablet could be as simple as wrapping it in cling wrap.

That’s Illan Kramer’s … hope. Kramer and colleagues have just invented a new way to spray solar cells onto flexible surfaces using miniscule light-sensitive materials known as colloidal quantum dots (CQDs) — a major step toward making spray-on solar cells easy and cheap to manufacture.

A Dec. 4, 2014 University of Toronto news release (also on EurekAlert) by Marit Mitchell, which originated the news item, gives a bit more detail about the technology (Note: Links have been removed),

 Solar-sensitive CQDs printed onto a flexible film could be used to coat all kinds of weirdly-shaped surfaces, from patio furniture to an airplane’s wing. A surface the size of a car roof wrapped with CQD-coated film would produce enough energy to power three 100-watt light bulbs – or 24 compact fluorescents.

He calls his system sprayLD, a play on the manufacturing process called ALD, short for atomic layer deposition, in which materials are laid down on a surface one atom-thickness at a time.

Until now, it was only possible to incorporate light-sensitive CQDs onto surfaces through batch processing – an inefficient, slow and expensive assembly-line approach to chemical coating. SprayLD blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic, like printing a newspaper by applying ink onto a roll of paper. This roll-to-roll coating method makes incorporating solar cells into existing manufacturing processes much simpler. In two recent papers in the journals Advanced Materials and Applied Physics Letters, Kramer showed that the sprayLD method can be used on flexible materials without any major loss in solar-cell efficiency.

Kramer built his sprayLD device using parts that are readily available and rather affordable – he sourced a spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store.

“This is something you can build in a Junkyard Wars fashion, which is basically how we did it,” says Kramer. “We think of this as a no-compromise solution for shifting from batch processing to roll-to-roll.”

“As quantum dot solar technology advances rapidly in performance, it’s important to determine how to scale them and make this new class of solar technologies manufacturable,” said Professor Ted Sargent, vice-dean, research in the Faculty of Applied Science & Engineering at University of Toronto and Kramer’s supervisor. “We were thrilled when this attractively-manufacturable spray-coating process also led to superior performance devices showing improved control and purity.”

In a third paper in the journal ACS Nano, Kramer and his colleagues used IBM’s BlueGeneQ supercomputer to model how and why the sprayed CQDs perform just as well as – and in some cases better than – their batch-processed counterparts. This work was supported by the IBM Canada Research and Development Centre, and by King Abdullah University of Science and Technology.

For those who would like to see the sprayLD device,

Here are links and citation for all three papers,

Efficient Spray-Coated Colloidal Quantum Dot Solar Cells by Illan J. Kramer, James C. Minor, Gabriel Moreno-Bautista, Lisa Rollny, Pongsakorn Kanjanaboos, Damir Kopilovic, Susanna M. Thon, Graham H. Carey, Kang Wei Chou, David Zhitomirsky, Aram Amassian, and Edward H. Sargent. Advanced Materials DOI: 10.1002/adma.201403281 Article first published online: 10 NOV 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Colloidal quantum dot solar cells on curved and flexible substrates by Illan J. Kramer, Gabriel Moreno-Bautista, James C. Minor, Damir Kopilovic, and Edward H. Sargent. Appl. Phys. Lett. 105, 163902 (2014); http://dx.doi.org/10.1063/1.4898635 Published online 21 October 2014

© 2014 AIP Publishing LLC

Electronically Active Impurities in Colloidal Quantum Dot Solids by Graham H. Carey, Illan J. Kramer, Pongsakorn Kanjanaboos, Gabriel Moreno-Bautista, Oleksandr Voznyy, Lisa Rollny, Joel A. Tang, Sjoerd Hoogland, and Edward H. Sargent. ACS Nano, 2014, 8 (11), pp 11763–11769 DOI: 10.1021/nn505343e Publication Date (Web): November 6, 2014

Copyright © 2014 American Chemical Society

All three papers are behind paywalls.

Given the publication dates for the papers, this looks like an attempt to get some previously announced research noticed by sending out a summary news release using a new ‘hook’ to get attention. I hope it works for them as it must be disheartening to have your research sink into obscurity because the announcements were issued during one or more busy news cycles.

One final note, if I understand the news release correctly, this work is still largely theoretical as there don’t seem to have been any field tests.

Inventions Nanotech Middle East conference in 2013

It’s a bit early to be talking about this conference since there isn’t much information, no speakers, no programme, etc. but there’s still time to pull that all together since the Inventions Nanotech Middle East Conference (aka, Inventions Nanotech ME) is scheduled for Nov. 3-5, 2013. From the Conference Overview page,

The Conference will host top notch industry experts from all over the world who will address the following crucial topics through live demonstrations and case studies:

Energy / Oil & Gas
Consumer Products

The event will be held at the Qatar National Convention Center.

There are two main sources of nanotech news items in that region. Iran or INIC  (Iran Nanotechnology Initiative Council [my Dec. 27, 2012 posting]), which continuously publicizes its nanotechnology research, and Saudi Arabia (KAUST or King Abdullah University of Science and Technology), which publicizes its work on solar energy (my July 30, 2012 posting), for the most part.

Good luck to the conference organizers.

Hands off the bubbles in my boiling water!

The discovery that boiling water bubbled was important to me. I’ve never really thought about it until now when researchers at Northwestern University have threatened to take my bubbles away, metaphorically speaking. From the Sept. 13, 2012 news item on ScienceDaily,

Every cook knows that boiling water bubbles, right? New research from Northwestern University turns that notion on its head.

“We manipulated what has been known for a long, long time by using the right kind of texture and chemistry to prevent bubbling during boiling,” said Neelesh A. Patankar, professor of mechanical engineering at Northwestern’s McCormick School of Engineering and Applied Science and co-author of the study.

This discovery could help reduce damage to surfaces, prevent bubbling explosions and may someday be used to enhance heat transfer equipment, reduce drag on ships and lead to anti-frost technologies.

The Sept. 13, 2012 news release from McCormick University (which originated the news item) provides details,

This phenomenon is based on the Leidenfrost effect. In 1756 the German scientist Johann Leidenfrost observed that water drops skittered on a sufficiently hot skillet, bouncing across the surface of the skillet on a vapor cushion or film of steam. The vapor film collapses as the surface falls below the Leidenfrost temperature. When the water droplet hits the surface of the skillet, at 100 degrees Celsius, boiling temperature, it bubbles.

To stabilize a Leidenfrost vapor film and prevent bubbling during boiling, Patankar collaborated with Ivan U. Vakarelski of King Abdullah University of Science and Technology, Saudi Arabia. Vakarelski led the experiments and Patankar provided the theory. The collaboration also included Derek Chan, professor of mathematics and statistics from the University of Melbourne in Australia.

In their experiments, the stabilization of the Leidenfrost vapor film was achieved by making the surface of tiny steel spheres very water-repellant. The spheres were sprayed with a commercially available hydrophobic coating — essentially self-assembled nanoparticles — combined with other water-hating chemicals to achieve the right amount of roughness and water repellency. At the correct length scale this coating created a surface texture full of tiny peaks and valleys.

When the steel spheres were heated to 400 degrees Celsius and dropped into room temperature water, water vapors formed in the valleys of the textured surface, creating a stable Leidenfrost vapor film that did not collapse once the spheres cooled to the temperature of boiling water. In the experiments, researchers completely avoided the bubbly phase of boiling.

To contrast, the team also coated tiny steel spheres with a water-loving coating, heated the objects to 700 degrees Celsius, dropped them into room temperature water and observed that the Leidenfrost vapor collapsed with a vigorous release of bubbles.

The scientists have provided a video illustrating their work,

This movie shows the cooling of 20 mm hydrophilic (left) and superhydrophobic (right) steel spheres in 100 C water. The spheres’ initial temperature is about 380 C. The bubbling phase of boiling is completely eliminated for steel spheres with superhydrophobic coating. (from Vimeo, http://vimeo.com/49391913)

I understand there are advantages to not having bubbles in hot water but it somehow seems wrong. I’ve given up a lot over the years: gravity, boundaries between living and non-living (that was a very big thing to give up), and other distinctions that I have made based on traditional science but, today, this is one step too far.

It may seem silly but that memory of my mother explaining that you identify boiling water by its bubbles is important to me. It was one of my first science lessons. I imagine I will recover from this moment but it does remind me of how challenging it can be when your notions of reality/normalcy are challenged by various scientific endeavours. The process can get quite exhausting as you keep recalibrating everything you ‘know’ all the time.

Colloidal quantum dot film from the University of Toronto and KAUST certified world’s most efficient

In my Sept. 20, 2011 posting, I featured an item about Ted Sargent ‘s (University of Toronto, Canada) work on colloidal quantum dot films. These films have now been certified as the world’s most efficient. There seems to be a lot of excitement given that these films have achieved a 7% efficiency rating. From the July 30, 2012 news item by Will Soutter on Azonano,

A team of scientists from the King Abdullah University of Science & Technology (KAUST) and University of Toronto (U of T) headed by Ted Sargent, an U of T Engineering Professor, has achieved a significant progress in the advancement of colloidal quantum dot (CQD) films, which in turn results in a CQD solar cell with an unprecedented efficiency of 7%.

The July 30, 2012 news release from the University of Toronto provides more detail,

“Previously, quantum dot solar cells have been limited by the large internal surface areas of the nanoparticles in the film, which made extracting electricity difficult,” said Dr. Susanna Thon, a lead co-author of the paper. “Our breakthrough was to use a combination of organic and inorganic chemistry to completely cover all of the exposed surfaces.”

The U of T cell represents a 37% increase in efficiency over the previous certified record. In order to improve efficiency, the researchers needed a way to both reduce the number of “traps” for electrons associated with poor surface quality while simultaneously ensuring their films were very dense to absorb as much light as possible. The solution was a so-called “hybrid passivation” scheme.

“By introducing small chlorine atoms immediately after synthesizing the dots, we’re able to patch the previously unreachable nooks and crannies that lead to electron traps,” explained doctoral student and lead co-author Alex Ip. “We follow that by using short organic linkers to bind quantum dots in the film closer together.”

Work led by Professor Aram Amassian of KAUST showed that the organic ligand exchange was necessary to achieve the densest film.

“The KAUST group used state-of-the-art synchrotron methods with sub-nanometer resolution to discern the structure of the films and prove that the hybrid passivation method led to the densest films with the closest-packed nanoparticles,” stated Professor Amassian.

I think the excitement over 7% indicates just how much hard work the researchers have accomplished to achieve this efficiency. It reminds me of reading about the early development of electricity (Power struggles; Scientific authority and the creation of practical electricity before Edison by Michael Brian Schiffer)  where accomplishments we would now consider minuscule built careers.

University of Toronto, KAUST, Pennsylvania State University and quantum colloidal dots

I’ve written about colloidal quantum dot solar cells and University of Toronto professor Ted Sargent’s work before (June 28, 2011). He and his team have been busy again. From the Sept. 18, 2011 news item on Nanowerk,

Researchers from the University of Toronto (U of T), King Abdullah University of Science & Technology (KAUST) and Pennsylvania State University (Penn State) have created the most efficient colloidal quantum dot (CQD) solar cell ever.

The discovery is reported in the latest issue of Nature Materials.

The first time (June 28)  I wrote about the colloidal quantum dot (CQD) solar cells, the team had made a breakthrough with the architecture of the solar cell by creating what they called a ‘graded recombination layer’ allowing infrared and visible light harvesters to be linked without compromising either layer. The next time I wrote about Sargent’s work  (July 11, 2011),  it concerned self-assembling quantum dots and DNA.

The very latest work is focussed on making the CQD solar cells more efficient by packing them closer together,

Until now, quantum dots have been capped with organic molecules that separate the nanoparticles by a nanometer. On the nanoscale, that is a long distance for electrons to travel.

To solve this problem, the researchers utilized inorganic ligands, sub-nanometer-sized atoms that bind to the surfaces of the quantum dots and take up less space. The combination of close packing and charge trap elimination enabled electrons to move rapidly and smoothly through the solar cells, thus providing record efficiency.

I gather this last breakthrough has made commercialization possible,

As a result of the potential of this research discovery, a technology licensing agreement has been signed by U of T and KAUST, brokered by MaRS Innovations (MI), which will enable the global commercialization of this new technology.

Here’s the competitive advantage that a CQD solar cell offers,

Quantum dots are nanoscale semiconductors that capture light and convert it into electrical energy. Because of their small scale, the dots can be sprayed onto flexible surfaces, including plastics. This enables the production of solar cells that are less expensive than the existing silicon-based version.


There are more details about this latest breakthrough both in the Nanowerk news item and in this University of Toronto Sept.19, 2011 news release credited to Liam Mitchell. For anyone who’s curious about MaRS, it’s located in Toronto, Ontario and seems to be some sort of technology company incubator or here’s how they describe themselves (from their How did MaRS get started page?),

A charitable organization could be created to better connect the worlds of science, business and government. A public-private partnership with a mission to remove the barriers between silos. Nurture a culture of innovation. And help create global enterprises that would contribute to Canada’s economic and social development.

University of Toronto research team’s efficient tandem solar cell with colloidal quantum dots (CQD)

Professor Ted Sargent, electrical and computer engineering professor at the University of Toronto, heads an engineering research team which recently published a paper about solar cells and colloidal quantum dots (CQD) in Nature Photonics. From Wayne MacPhail’s June 27, 2011 news release for the University of Toronto,

The researchers, led by Professor Ted Sargent of electrical and computer engineering, report the first efficient tandem solar cell based on colloidal quantum dots (CQD). “The U of T device is a stack of two light-absorbing layers – one tuned to capture the sun’s visible rays, the other engineered to harvest the half of the sun’s power that lies in the infrared,” said lead co-author Xihua Wang, a post-doctoral fellow.

“We needed a breakthrough in architecting the interface between the visible and infrared junction,” said Sargent, Canada Research Chair in Nanotechnology. “The team engineered a cascade – really a waterfall – of nanometers-thick materials to shuttle electrons between the visible and infrared layers.”

According to doctoral student Ghada Koleilat, lead co-author of the paper, “We needed a new strategy – which we call the graded recombination layer – so that our visible and infrared light harvesters could be linked together efficiently, without any compromise to either layer.” [emphasis mine]

The team pioneered solar cells made using CQDs, nanoscale materials that can readily be tuned to respond to specific wavelengths of the visible and invisible spectrum. By capturing such a broad range of light waves – wider than normal solar cells – tandem CQD solar cells can in principle reach up to 42 per cent efficiencies. The best single-junction solar cells are constrained to a maximum of 31 per cent efficiency. In reality, solar cells that are on the roofs of houses and in consumer products have 14 to 18 per cent efficiency. The work expands the Toronto team’s world-leading 5.6 per cent efficient colloidal quantum dot solar cells.

According to the University of Toronto news item and the June 28, 2011 news item by Cameron Chai on Azonano, Sargent believes that this ‘graded recombination layer’ will be found in building materials and mobile devices in five years.

It’s always informative to look at the funding agencies for these projects. The CQD project received its funding from King Abdullah University of Science and Technology (KAUST) [mentioned in my Sept. 24, 2009 posting—scroll down 1/2 way), by the Ontario Research Fund Research Excellence Program and by the Natural Sciences and Engineering Research Council (NSERC) of Canada.

ETA July 4, 2011: You can get another take on this work from Dexter Johnson, Nanoclast blog on the IEEE website in his June 28, 2011 posting, Harvesting Visible and Invisible Light in PVs with Colloidal Quantum Dots.