Tag Archives: King Abdullah University of Science and Technology (KAUST)

Centuries-old technique for constructing arched stone windows leads to new technique for nanoscale windows

An October 2, 2023 news item on phys.org announces research from Saudi Arabia,

A centuries-old technique for constructing arched stone windows has inspired a new way to form tailored nanoscale windows in porous functional materials called metal-organic frameworks (MOFs).

I very much appreciate the aesthetics of the illustration for the research,

Caption: KAUST researchers have developed a new approach to MOF design that offers multiple benefits to enhance MOF performance. Credit: © 2023 KAUST.

An October 2, 2023 King Abdullah University of Science & Technology (KAUST) press release (also on EurekAlert), which originated the news item, provides more technical details about the research, Note: A link has been removed,

The method uses a molecular version of an architectural arch-forming “centring formwork“ template to direct the formation of MOFs with pore windows of predetermined shape and size.[1]. New MOFs designed and made in this way range from narrow-windowed materials with gas separation potential to larger-windowed structures with potential medical applications due to their excellent oxygen-adsorption capacity.

“One of the most challenging goals in new structure design is the precise control of structure formation,” says Aleksandr Sapianik, a postdoc in the group of Mohamed Eddaoudi, who led the research. For reticular chemistry — the assembly of molecular building blocks into porous crystalline materials such as MOFs — the centering formwork concept might offer that precise control, the team realized.

The starting point of the research was a zeolite-like MOF (ZMOF), which usually features pentagonal windows framed by building blocks called supertetrahedra (ST). “Our goal was to control ST arrangement to change from this well-known topology to one not reported before with these building blocks,” Sapianik says.

The team developed centring structure-directing agents (cSDA) to control ST alignment and form ZMOF windows of new shapes and sizes. One set of cSDAs, designed to tighten the angle between adjoining ST units, created small windows. Another set, designed to expand the angle between ST units, gave larger windows.

“MOF pore size and volume are important parameters that affect their application,” says Marina Barsukova, a postdoc in Eddaoudi’s team. One large-windowed ZMOF the team designed, Fe-sod-ZMOF-320, showed the highest oxygen adsorption capacity of any MOF known. “This property is important in the medical and aerospace industries, where the high capacity would increase oxygen storage in a cylinder, or enable smaller cylinders for easier transport,” Barsukova says. The same ZMOFs also performed well for storage of methane and hydrogen, which are potential fuels. Other ZMOFs in the family with narrow windows showed potential for gas separation of molecular mixtures.

The cSDA concept offers multiple benefits enhancing MOF performance, says Vincent Guillerm, a research scientist in Eddaoudi’s group. “The cSDA partitions big windows into smaller ones, which our preliminary results suggest will be useful for chemical separations,” he says. “It also offers additional internal pore surface, which can help to improve gas storage, and reinforces the MOF framework, which should improve the material’s stability,” he adds.

“The centring approach we have developed is another powerful strategy in the repertoire of reticular chemistry, offering great potential for made-to-order MOFs for applications in energy security and environmental sustainability,” Eddaoudi says.

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

Face-directed assembly of tailored isoreticular MOFs using centring structure-directing agents by Marina Barsukova, Aleksandr Sapianik, Vincent Guillerm, Aleksander Shkurenko, Aslam C. Shaikh, Prakash Parvatkar, Prashant M. Bhatt, Mickaele Bonneau, Abdulhadi Alhaji, Osama Shekhah, Salvador R. G. Balestra, Rocio Semino, Guillaume Maurin & Mohamed Eddaoudi. Nature Synthesis (2023) DOI: https://doi.org/10.1038/s44160-023-00401-8 Published: 02 October 2023

This paper is open access.

Organic neuromorphic electronics

A December 13, 2021 news item on ScienceDaily describes some research from Germany’s Max Planck Institute for Polymer Research,

The human brain works differently from a computer – while the brain works with biological cells and electrical impulses, a computer uses silicon-based transistors. Scientists have equipped a toy robot with a smart and adaptive electrical circuit made of soft organic materials, similarly to the biological matter. With this bio-inspired approach, they were able to teach the robot to navigate independently through a maze using visual signs for guidance.

A December 13, 2021 Max Planck Institute for Polymer Research press release (also on EurekAlert), which originated the news item, fills in a few details,

The processor is the brain of a computer – an often-quoted phrase. But processors work fundamentally differently than the human brain. Transistors perform logic operations by means of electronic signals. In contrast, the brain works with nerve cells, so-called neurons, which are connected via biological conductive paths, so-called synapses. At a higher level, this signaling is used by the brain to control the body and perceive the surrounding environment. The reaction of the body/brain system when certain stimuli are perceived – for example, via the eyes, ears or sense of touch – is triggered through a learning process. For example, children learn not to reach twice for a hot stove: one input stimulus leads to a learning process with a clear behavioral outcome.

Scientists working with Paschalis Gkoupidenis, group leader in Paul Blom’s department at the Max Planck Institute for Polymer Research, have now applied this basic principle of learning through experience in a simplified form and steered a robot through a maze using a so-called organic neuromorphic circuit. The work was an extensive collaboration between the Universities of Eindhoven [Eindhoven University of Technology; Netherlands], Stanford [University; California, US], Brescia [University; Italy], Oxford [UK] and KAUST [King Abdullah University of Science and Technology, Saudi Arabia].

“We wanted to use this simple setup to show how powerful such ‘organic neuromorphic devices’ can be in real-world conditions,” says Imke Krauhausen, a doctoral student in Gkoupidenis’ group and at TU Eindhoven (van de Burgt group), and first author of the scientific paper.

To achieve the navigation of the robot inside the maze, the researchers fed the smart adaptive circuit with sensory signals coming from the environment. The path of maze towards the exit is indicated visually at each maze intersects. Initially, the robot often misinterprets the visual signs, thus it makes the wrong “turning” decisions at the maze intersects and loses the way out. When the robot takes these decisions and follows wrong dead-end paths, it is being discouraged to take these wrong decisions by receiving corrective stimuli. The corrective stimuli, for example when the robot hits a wall, are directly applied at the organic circuit via electrical signals induced by a touch sensor attached to the robot. With each subsequent execution of the experiment, the robot gradually learns to make the right “turning” decisions at the intersects, i. e. to avoid receiving corrective stimuli, and after a few trials it finds the way out of the maze. This learning process happens exclusively on the organic adaptive circuit. 

“We were really glad to see that the robot can pass through the maze after some runs by learning on a simple organic circuit. We have shown here a first, very simple setup. In the distant future, however, we hope that organic neuromorphic devices could also be used for local and distributed computing/learning. This will open up entirely new possibilities for applications in real-world robotics, human-machine interfaces and point-of-care diagnostics. Novel platforms for rapid prototyping and education, at the intersection of materials science and robotics, are also expected to emerge.” Gkoupidenis says.

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

Organic neuromorphic electronics for sensorimotor integration and learning in robotics by Imke Krauhausen, Dimitrios A. Koutsouras, Armantas Melianas, Scott T. Keene, Katharina Lieberth, Hadrien Ledanseur, Rajendar Sheelamanthula, Alexander Giovannitti, Fabrizio Torricelli, Iain Mcculloch, Paul W. M. Blom, Alberto Salleo, Yoeri van de Burgt and Paschalis Gkoupidenis. Science Advances • 10 Dec 2021 • Vol 7, Issue 50 • DOI: 10.1126/sciadv.abl5068

This paper is open access.

Turning wasted energy back into electricity

This work comes from the King Abdullah University of Science and Technology (KAUST; Saudi Arabia). From a June 27, 2019 news item on Nanowerk (Note: A link has been removed),

Some of the vast amount of wasted energy that machines and devices emit as heat could be recaptured using an inexpensive nanomaterial developed at KAUST. This thermoelectric nanomaterial could capture the heat lost by devices, ranging from mobile phones to vehicle engines, and turn it directly back into useful electricity (Advanced Energy Materials, “Low-temperature-processed colloidal quantum dots as building blocks for thermoelectrics”).

A June 27, 2019 KAUST press release, which originated the news item, provides more detail,

The nanomaterial is made using a low-temperature solution-based production process, making it suitable for coating on flexible plastics for use almost anywhere.

“Among the many renewable energy sources, waste heat has not been widely considered,” says Mohamad Nugraha, a postdoctoral researcher in Derya Baran’s lab. Waste heat emitted by machines and devices could be recaptured by thermoelectric materials. These substances have a property that means that when one side of the material is hot and the other is cold, an electric charge builds up along the temperature gradient.

Until now, thermoelectric materials have been made using expensive and energy-intensive processes. Baran, Nugraha and their colleagues have developed a new thermoelectric material made by spin coating a liquid solution of nanomaterials called quantum dots.

The team spin coated a thin layer of lead-sulphide quantum dots on a surface and then added a solution of short linker ligands that crosslink the quantum dots together to enhance the material’s electronic properties.

After repeating the spin-coating process layer by layer to form a 200-nanometer-thick film, gentle thermal annealing dried the film and completed fabrication. “Thermoelectric research has focused on materials processed at very high temperatures, above 400 degrees Celsius,” Nugraha says. The quantum-dot-based thermoelectric material is only heated up to 175 degrees Celsius. This lower processing temperature could cut production costs and means that thermoelectric devices could be formed on a broad range of surfaces, including cheap flexible plastics.

The team’s material showed promising thermoelectric properties. One important parameter of a good thermoelectric is the Seebeck coefficient, which corresponds to the voltage generated when a temperature gradient is applied. “We found some key factors leading to the enhanced Seebeck coefficient in our materials,” Nugraha says.

The team was also able to show that an effect called the quantum confinement, which alters a material’s electronic properties when it is shrunk to the nanoscale, was important for enhancing the Seebeck coefficient. The discovery is a step toward practical high-performance, low-temperature, solution-processed thermoelectric generators, Nugraha says.

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

Low‐Temperature‐Processed Colloidal Quantum Dots as Building Blocks for Thermoelectrics by Mohamad I. Nugraha, Hyunho Kim, Bin Sun, Md Azimul Haque, Francisco Pelayo Garcia de Arquer, Diego Rosas Villalva, Abdulrahman El‐Labban, Edward H. Sargent, Husam N. Alshareef, Derya Baran. Advanced Energy Materials Volume 9, Issue 13 1803049 April 4, 2019 DOI: https://doi.org/10.1002/aenm.201803049 First published [online]: 14 February 2019

This paper is behind a paywall.

Structural colo(u)r from transparent 3D printed nanostructures

Caption: Light hits the 3-D printed nanostructures from below. After it is transmitted through, the viewer sees only green light — the remaining colors are redirected. Credit: Thomas Auzinger [downloaded from http://visualcomputing.ist.ac.at/publications/2018/StructCol/]

An August 17, 2018 news item on ScienceDaily announces the work illustrated by the image above,

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and certain color effects are impossible to achieve. The natural world, however, also exhibits structural coloration, where the microstructure of an object causes various colors to appear. Peacock feathers, for instance, are pigmented brown, but — because of long hollows within the feathers — reflect the gorgeous, iridescent blues and greens we see and admire. Recent advances in technology have made it practical to fabricate the kind of nanostructures that result in structural coloration, and computer scientists from the Institute of Science and Technology Austria (IST Austria) and the King Abdullah University of Science and Technology (KAUST) have now created a computational tool that automatically creates 3D-print templates for nanostructures that correspond to user-defined colors. Their work demonstrates the great potential for structural coloring in industry, and opens up possibilities for non-experts to create their own designs. This project will be presented at this year’s top computer graphics conference, SIGGRAPH 2018, by first author and IST Austria postdoc Thomas Auzinger. This is one of five IST Austria presentations at the conference this year.

SIGGRAPH 2018, now ended, was mentioned in my Aug. 9, 2018 posting.but since this presentation is accompanied by a paper, it rates its own posting. For one more excuse, there’s my fascination with structural colour.

An August 17, 2018 Institute of Science and Technology Austria press release (also on EurekAlert), which originated the news item, delves into the work,

The changing colors of a chameleon and the iridescent blues and greens of the morpho butterfly, among many others in nature, are the result of structural coloration, where nanostructures cause interference effects in light, resulting in a variety of colors when viewed macroscopically. Structural coloration has certain advantages over coloring with pigments (where particular wavelengths are absorbed), but until recently, the limits of technology meant fabricating such nanostructures required highly specialized methods. New “direct laser writing” set-ups, however, cost about as much as a high-quality industrial 3D printer, and allow for printing at the scale of hundreds of nanometers (hundred to thousand time thinner than a human hair), opening up possibilities for scientists to experiment with structural coloration.

So far, scientists have primarily experimented with nanostructures that they had observed in nature, or with simple, regular nanostructural designs (e.g. row after row of pillars). Thomas Auzinger and Bernd Bickel of IST Austria, together with Wolfgang Heidrich of KAUST, however, took an innovative new approach that differs in several key ways. First, they solve the inverse design task: the user enters the color they want to replicate, and then the computer creates a nanostructure pattern that gives that color, rather than attempting to reproduce structures found in nature. Moreover, “our design tool is completely automatic,” says Thomas Auzinger. “No extra effort is required on the part of the user.”

Second, the nanostructures in the template do not follow a particular pattern or have a regular structure; they appear to be randomly composed—a radical break from previous methods, but one with many advantages. “When looking at the template produced by the computer I cannot tell by the structure alone, if I see a pattern for blue or red or green,” explains Auzinger. “But that means the computer is finding solutions that we, as humans, could not. This free-form structure is extremely powerful: it allows for greater flexibility and opens up possibilities for additional coloring effects.” For instance, their design tool can be used to print a square that appears red from one angle, and blue from another (known as directional coloring).

Finally, previous efforts have also stumbled when it came to actual fabrication: the designs were often impossible to print. The new design tool, however, guarantees that the user will end up with a printable template, which makes it extremely useful for the future development of structural coloration in industry. “The design tool can be used to prototype new colors and other tools, as well as to find interesting structures that could be produced industrially,” adds Auzinger. Initial tests of the design tool have already yielded successful results. “It’s amazing to see something composed entirely of clear materials appear colored, simply because of structures invisible to the human eye,” says Bernd Bickel, professor at IST Austria, “we’re eager to experiment with additional materials, to expand the range of effects we can achieve.”

“It’s particularly exciting to witness the growing role of computational tools in fabrication,” concludes Auzinger, “and even more exciting to see the expansion of ‘computer graphics’ to encompass physical as well as virtual images.”

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

Computational Design of Nanostructural Color for Additive Manufacturing by Thomas Auzinger, Wolfgang Heidrich, and Bernd Bickel. ACM Trans. Graph. 37, 4, Article 159 (August 2018). 16 pages. doi.org/10.1145/3197517.3201376

This appears to be open access.

There is also a project page bearing the same title as the paper, Computational Design of Nanostructural Color for Additive Manufacturing.