Scientists at Northwestern University (Chicago, Illinois) and the California Institute of Technology (CalTech) have developed what could be a more sustainable way to produce electricity. From a July 31, 2019 news item on Nanowerk,
Scientists from Northwestern University and Caltech have produced electricity by simply flowing water over extremely thin layers of inexpensive metals, including iron, that have oxidized. These films represent an entirely new way of generating electricity and could be used to develop new forms of sustainable power production.
The films have a conducting metal nanolayer (10 to 20 nanometers thick) that is insulated with an oxide layer (2 nanometers thick). Current is generated when pulses of rainwater and ocean water alternate and move across the nanolayers. The difference in salinity drags the electrons along in the metal below.
“It’s the oxide layer over the nanometal that really makes this device go,” said Franz M. Geiger, the Dow Professor of Chemistry in Northwestern’s Weinberg College of Arts and Sciences. “Instead of corrosion, the presence of the oxides on the right metals leads to a mechanism that shuttles electrons.”
The films are transparent, a feature that could be taken advantage of in solar cells. The researchers intend to study the method using other ionic liquids, including blood. Developments in this area could lead to use in stents and other implantable devices.
“The ease of scaling up the metal nanolayer to large areas and the ease with which plastics can be coated gets us to three-dimensional structures where large volumes of liquids can be used,” Geiger said. “Foldable designs that fit, for instance, into a backpack are a possibility as well. Given how transparent the films are, it’s exciting to think about coupling the metal nanolayers to a solar cell or coating the outside of building windows with metal nanolayers to obtain energy when it rains.”
The study, titled “Energy Conversion via Metal Nanolayers,” was published this week [on July 29, 2019] in the journal Proceedings of the National Academy of Sciences (PNAS).
Geiger is the study’s corresponding author; his Northwestern team conducted the experiments. Co-author Thomas Miller, professor of chemistry at Caltech, led a team that conducted atomistic simulations to study the device’s behavior at the atomic level.
The new method produces voltages and currents comparable to graphene-based devices reported to have efficiencies of around 30% — similar to other approaches under investigation (carbon nanotubes and graphene) but with a single-step fabrication from earth-abundant elements instead of multistep fabrication. This simplicity allows for scalability, rapid implementation and low cost. Northwestern has filed for a provisional patent.
Of the metals studied, the researchers found that iron, nickel and vanadium worked best. They tested a pure rust sample as a control experiment; it did not produce a current.
The mechanism behind the electricity generation is complex, involving ion adsorption and desorption, but it essentially works like this: The ions present in the rainwater/saltwater attract electrons in the metal beneath the oxide layer; as the water flows, so do those ions, and through that attractive force, they drag the electrons in the metal along with them, generating an electrical current.
“There are interesting prospects for a variety of energy and sustainability applications, but the real value is the new mechanism of oxide-metal electron transfer,” Geiger said. “The underlying mechanism appears to involve various oxidation states.”
The team used a process called physical vapor deposition (PVD), which turns normally solid materials into a vapor that condenses on a desired surface. PVD allowed them to deposit onto glass metal layers only 10 to 20 nanometers thick. An oxide layer then forms spontaneously in air. It grows to a thickness of 2 nanometers and then stops growing.
“Thicker films of metal don’t succeed — it’s a nano-confinement effect,” Geiger said. “We have discovered the sweet spot.”
When tested, the devices generated several tens of millivolts and several microamps per centimeter squared.
“For perspective, plates having an area of 10 square meters each would generate a few kilowatts per hour — enough for a standard U.S. home,” Miller said. “Of course, less demanding applications, including low-power devices in remote locations, are more promising in the near term.”
Here’s a link to and a citation for the paper,
Energy conversion via metal nanolayers by Mavis D. Boamah, Emilie H. Lozier, Jeongmin Kim, Paul E. Ohno, Catherine E. Walker, Thomas F. Miller III, and Franz M. Geiger. PNAS DOI: https://doi.org/10.1073/pnas.1906601116 First published July 29, 2019
Just when I thought I’d seen all the carbon nanotube abbreviations; I find two new ones in my first news bit about adhesion. Later, I’m including a second news bit that has to do with the upcoming American Chemical Society (ACS) Meeting in San Diego, California.
Sticky carbon nanotubes (CNTs)
Scientists have developed an adhesive that retains its stickiness in extreme temperatures according to a July 10, 2019 news item on Nanowerk (Note: A link has been removed),
In very hot or cold environments, conventional tape can lose its stickiness and leave behind an annoying residue. But while most people can avoid keeping taped items in a hot car or freezer, those living in extreme environments such as deserts and the Antarctic often can’t avoid such conditions.
Now, researchers reporting in ACS’ journal Nano Letters (“Continuous, Ultra-lightweight, and Multipurpose Super-aligned Carbon Nanotube Tapes Viable over a Wide Range of Temperatures”) say they have developed a new nanomaterial tape that can function over a wide temperature range.
In previous work, researchers have explored using nanomaterials, such as vertically aligned multi-walled carbon nanotubes (VA-MWNTs), to make better adhesive tapes. Although VA-MWNTs are stronger than conventional tapes at both high and low temperatures, the materials are relatively thick, and large amounts can’t be made cost-effectively.
These are my first vertically aligned multi-walled carbon nanotubes (VA-MWNTs) and superaligned carbon nanotubes (SACNTs). I was a little surprised that VA-MWNTs didn’t include the C since these are carbon nanotubes (CNTs) and there are other types of nanotubes. So, I searched and found that inclusion of the letter ‘C’ for carbon seems to be discretionary. Moving on.
… Kai Liu, Xide Li, Wenhui Duan, Kaili Jiang and coworkers wondered if they could develop a new type of tape composed of superaligned carbon nanotube (SACNT) films. As their name suggests, SACNTs are nanotubes that are precisely aligned parallel to each other, capable of forming ultrathin but strong yarns or films.
To make their tape, the researchers pulled a film from the interior of an array of SACNTs — similar to pulling a strip of tape from a roll. The resulting double-sided tape could adhere to surfaces through van der Waals interactions, which are weak electric forces generated between two atoms or molecules that are close together. The ultrathin, ultra-lightweight and flexible tape outperformed conventional adhesives, at temperatures ranging from -321 F to 1,832 F. Researchers could remove the tape by peeling it off, soaking it in acetone or burning it, with no noticeable residues. The tape adhered to many different materials such as metals, nonmetals, plastics and ceramics, but it stuck more strongly to smooth than rough surfaces, similar to regular tape. The SACNT tape can be made cost-effectively in large amounts. In addition to performing well in extreme environments, the new tape might be useful for electronic components that heat up during use, the researchers say.
American Chemical Society (ACS) National Meeting in San Diego, Aug. 25to 29, 2019: an invite to journalists
A July 18, 2019 ACS press release (received via email) announced their upcoming meeting and it included an invitation to journalists. (ACS has two meetings per year, one on the East Coast and the other on the West, roughly speaking).
Materials science and nanotechnology topics at the upcoming 2019 American Chemical Society national meeting in San Diego
WASHINGTON, July 18, 2019 — Journalists who register for the American Chemical Society’s (ACS’) Fall 2019 National Meeting & Exposition in San Diego will have access to more than 9,500 presentations on the meeting’s theme, “Chemistry & Water,” will include nanotechnology and materials science topics. The meeting, one of the largest scientific conferences of the year, will be held Aug. 25 to 29  in San Diego.
Nobel Prize winner Frances Arnold, Ph.D., of the California Institute of Technology and Thomas Markland, DPhil, of Stanford University will deliver the two Kavli Foundation lectures on Aug. 26 .
The more than 9,500 presentations will include presentations on nanotechnology and materials science, such as:
Colloids and nanomaterials for water purification Nanozymes for bioanalysis and beyond The latest in wearable and implantable sensors Nanoscale and molecular assemblies: designing matter to control energy transport Colloidal quantum dots for solar and other emerging technologies Nanoscience of bourbon Targeted delivery of nanomedicines Advances in nanocellulose research for engineered functionality Water sustainability through nanotechnology
ACS will operate a press center with press conferences, a news media workroom fully staffed to assist in arranging interviews and free Wi-Fi, computers and refreshments.
Embargoed copies of press releases and a press conference schedule will be available in mid-August. Reporters planning to cover the meeting from their home bases will have access to the press conferences on YouTube at http://bit.ly/acs2019sandiego.
ACS considers requests for press credentials and complimentary registration to national meetings from reporters (staff and freelance) and public information officers at government, non-profit and educational institutions. See the website for details.
The ACS provides complimentary registration to national meetings to reporters (staff and freelancers) and public information officers from government, non-profit and educational institutions. Marketing and public relations professionals, lobbyists and scientists do not qualify as press and must register via the main meeting registration page. Journal managing editors, book commissioning editors, acquisitions editors, publishers and those who do not produce news for a publication or institution also do not qualify. We reserve the right to refuse press credentials for any reason.
No bloggers, eh? it’s been a long time since I’ve seen a press registration process that doesn’t mention bloggers at all.
An April 18, 2018 news item on phys.org highlights an exciting graphene development at the Massachusetts Institute of Technology (MIT),
MIT engineers have developed a continuous manufacturing process that produces long strips of high-quality graphene.
The team’s results are the first demonstration of an industrial, scalable method for manufacturing high-quality graphene that is tailored for use in membranes that filter a variety of molecules, including salts, larger ions, proteins, or nanoparticles. Such membranes should be useful for desalination, biological separation, and other applications.
A new manufacturing process produces strips of graphene, at large scale, for use in membrane technologies and other applications. Image: Christine Daniloff, MIT
“For several years, researchers have thought of graphene as a potential route to ultrathin membranes,” says John Hart, associate professor of mechanical engineering and director of the Laboratory for Manufacturing and Productivity at MIT. “We believe this is the first study that has tailored the manufacturing of graphene toward membrane applications, which require the graphene to be seamless, cover the substrate fully, and be of high quality.”
Hart is the senior author on the paper, which appears online in the journal Applied Materials and Interfaces. The study includes first author Piran Kidambi, a former MIT postdoc who is now an assistant professor at Vanderbilt University; MIT graduate students Dhanushkodi Mariappan and Nicholas Dee; Sui Zhang of the National University of Singapore; Andrey Vyatskikh, a former student at the Skolkovo Institute of Science and Technology who is now at Caltech; and Rohit Karnik, an associate professor of mechanical engineering at MIT.
For many researchers, graphene is ideal for use in filtration membranes. A single sheet of graphene resembles atomically thin chicken wire and is composed of carbon atoms joined in a pattern that makes the material extremely tough and impervious to even the smallest atom, helium.
Researchers, including Karnik’s group, have developed techniques to fabricate graphene membranes and precisely riddle them with tiny holes, or nanopores, the size of which can be tailored to filter out specific molecules. For the most part, scientists synthesize graphene through a process called chemical vapor deposition, in which they first heat a sample of copper foil and then deposit onto it a combination of carbon and other gases.
Graphene-based membranes have mostly been made in small batches in the laboratory, where researchers can carefully control the material’s growth conditions. However, Hart and his colleagues believe that if graphene membranes are ever to be used commercially they will have to be produced in large quantities, at high rates, and with reliable performance.
“We know that for industrialization, it would need to be a continuous process,” Hart says. “You would never be able to make enough by making just pieces. And membranes that are used commercially need to be fairly big – some so big that you would have to send a poster-wide sheet of foil into a furnace to make a membrane.”
A factory roll-out
The researchers set out to build an end-to-end, start-to-finish manufacturing process to make membrane-quality graphene.
The team’s setup combines a roll-to-roll approach – a common industrial approach for continuous processing of thin foils – with the common graphene-fabrication technique of chemical vapor deposition, to manufacture high-quality graphene in large quantities and at a high rate. The system consists of two spools, connected by a conveyor belt that runs through a small furnace. The first spool unfurls a long strip of copper foil, less than 1 centimeter wide. When it enters the furnace, the foil is fed through first one tube and then another, in a “split-zone” design.
While the foil rolls through the first tube, it heats up to a certain ideal temperature, at which point it is ready to roll through the second tube, where the scientists pump in a specified ratio of methane and hydrogen gas, which are deposited onto the heated foil to produce graphene.
“Graphene starts forming in little islands, and then those islands grow together to form a continuous sheet,” Hart says. “By the time it’s out of the oven, the graphene should be fully covering the foil in one layer, kind of like a continuous bed of pizza.”
As the graphene exits the furnace, it’s rolled onto the second spool. The researchers found that they were able to feed the foil continuously through the system, producing high-quality graphene at a rate of 5 centimers per minute. Their longest run lasted almost four hours, during which they produced about 10 meters of continuous graphene.
“If this were in a factory, it would be running 24-7,” Hart says. “You would have big spools of foil feeding through, like a printing press.”
Once the researchers produced graphene using their roll-to-roll method, they unwound the foil from the second spool and cut small samples out. They cast the samples with a polymer mesh, or support, using a method developed by scientists at Harvard University, and subsequently etched away the underlying copper.
“If you don’t support graphene adequately, it will just curl up on itself,” Kidambi says. “So you etch copper out from underneath and have graphene directly supported by a porous polymer – which is basically a membrane.”
The polymer covering contains holes that are larger than graphene’s pores, which Hart says act as microscopic “drumheads,” keeping the graphene sturdy and its tiny pores open.
The researchers performed diffusion tests with the graphene membranes, flowing a solution of water, salts, and other molecules across each membrane. They found that overall, the membranes were able to withstand the flow while filtering out molecules. Their performance was comparable to graphene membranes made using conventional, small-batch approaches.
The team also ran the process at different speeds, with different ratios of methane and hydrogen gas, and characterized the quality of the resulting graphene after each run. They drew up plots to show the relationship between graphene’s quality and the speed and gas ratios of the manufacturing process. Kidambi says that if other designers can build similar setups, they can use the team’s plots to identify the settings they would need to produce a certain quality of graphene.
“The system gives you a great degree of flexibility in terms of what you’d like to tune graphene for, all the way from electronic to membrane applications,” Kidambi says.
Looking forward, Hart says he would like to find ways to include polymer casting and other steps that currently are performed by hand, in the roll-to-roll system.
“In the end-to-end process, we would need to integrate more operations into the manufacturing line,” Hart says. “For now, we’ve demonstrated that this process can be scaled up, and we hope this increases confidence and interest in graphene-based membrane technologies, and provides a pathway to commercialization.”
Glasswinged butterfly. Greta oto. Credit: David Tiller/CC BY-SA 3.0
My jaw dropped on seeing this image and I still have trouble believing it’s real. (You can find more image of glasswinged butterflies here in an Cot. 25, 2014 posting on thearkinspace. com and there’s a video further down in the post.)
Inspired by tiny nanostructures on transparent butterfly wings, engineers at Caltech have developed a synthetic analogue for eye implants that makes them more effective and longer-lasting. A paper about the research was published in Nature Nanotechnology.
Sections of the wings of a longtail glasswing butterfly are almost perfectly transparent. Three years ago, Caltech postdoctoral researcher Radwanul Hasan Siddique–at the time working on a dissertation involving a glasswing species at Karlsruhe Institute of Technology in Germany–discovered the reason why: the see-through sections of the wings are coated in tiny pillars, each about 100 nanometers in diameter and spaced about 150 nanometers apart. The size of these pillars–50 to 100 times smaller than the width of a human hair–gives them unusual optical properties. The pillars redirect the light that strikes the wings so that the rays pass through regardless of the original angle at which they hit the wings. As a result, there is almost no reflection of the light from the wing’s surface.
In effect, the pillars make the wings clearer than if they were made of just plain glass.
That redirection property, known as angle-independent antireflection, attracted the attention of Caltech’s Hyuck Choo. For the last few years Choo has been developing an eye implant that would improve the monitoring of intra-eye pressure in glaucoma patients. Glaucoma is the second leading cause of blindness worldwide. Though the exact mechanism by which the disease damages eyesight is still under study, the leading theory suggests that sudden spikes in the pressure inside the eye damages the optic nerve. Medication can reduce the increased eye pressure and prevent damage, but ideally it must be taken at the first signs of a spike in eye pressure.
“Right now, eye pressure is typically measured just a couple times a year in a doctor’s office. Glaucoma patients need a way to measure their eye pressure easily and regularly,” says Choo, assistant professor of electrical engineering in the Division of Engineering and Applied Science and a Heritage Medical Research Institute Investigator.
Choo has developed an eye implant shaped like a tiny drum, the width of a few strands of hair. When inserted into an eye, its surface flexes with increasing eye pressure, narrowing the depth of the cavity inside the drum. That depth can be measured by a handheld reader, giving a direct measurement of how much pressure the implant is under.
One weakness of the implant, however, has been that in order to get an accurate measurement, the optical reader has to be held almost perfectly perpendicular–at an angle of 90 degrees (plus or minus 5 degrees)–with respect to the surface of the implant. At other angles, the reader gives an incorrect measurement.
And that’s where glasswing butterflies come into the picture. Choo reasoned that the angle-independent optical property of the butterflies’ nanopillars could be used to ensure that light would always pass perpendicularly through the implant, making the implant angle-insensitive and providing an accurate reading regardless of how the reader is held.
He enlisted Siddique to work in his lab, and the two, working along with Caltech graduate student Vinayak Narasimhan, figured out a way to stud the eye implant with pillars approximately the same size and shape of those on the butterfly’s wings but made from silicon nitride, an inert compound often used in medical implants. Experimenting with various configurations of the size and placement of the pillars, the researchers were ultimately able to reduce the error in the eye implants’ readings threefold.
“The nanostructures unlock the potential of this implant, making it practical for glaucoma patients to test their own eye pressure every day,” Choo says.
The new surface also lends the implants a long-lasting, nontoxic anti-biofouling property.
In the body, cells tend to latch on to the surface of medical implants and, over time, gum them up. One way to avoid this phenomenon, called biofouling, is to coat medical implants with a chemical that discourages the cells from attaching. The problem is that such coatings eventually wear off.
The nanopillars created by Choo’s team, however, work in a different way. Unlike the butterfly’s nanopillars, the lab-made nanopillars are extremely hydrophilic, meaning that they attract water. Because of this, the implant, once in the eye, is soon encased in a coating of water. Cells slide off instead of gaining a foothold.
“Cells attach to an implant by binding with proteins that are adhered to the implant’s surface. The water, however, prevents those proteins from establishing a strong connection on this surface,” says Narasimhan. Early testing suggests that the nanopillar-equipped implant reduces biofouling tenfold compared to previous designs, thanks to this anti-biofouling property.
Being able to avoid biofouling is useful for any implant regardless of its location in the body. The team plans to explore what other medical implants could benefit from their new nanostructures, which can be inexpensively mass produced.
ETA May 25, 2018: I’m obsessed. Here’s one more glasswing image,
Caption: The clear wings make this South-American butterfly hard to see in flight, a succesfull defense mechanism. Credit: Eddy Van 3000 from in Flanders fields – Belgiquistan – United Tribes ov Europe Date: 7 October 2007, 14:35 his file is licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license. [downloaded from https://commons.wikimedia.org/wiki/File:E3000_-_the_wings-become-windows_butterfly._(by-sa).jpg]
From a May 11, 2018 United Nations Educational, Scientific and Cultural Organization (UNESCO) press release (received via email),
UNESCO will welcome leading scientists on 16 May 2018 for the 1st edition of the International Day of Light (02:30-08:00 pm) to celebrate the role light plays in our daily lives. Researchers and intellectuals will examine how light-based technologies can contribute to meet pressing challenges in diverse areas, such as medicine, education, agriculture and energy.
UNESCO Director-General Audrey Azoulay will open this event, which will count with the participation of renowned scientists, including:
Kip Thorne, 2017 Nobel Prize in Physics, California Institute of Technology (United States of America).
Claude Cohen-Tannoudji, 1997 Nobel Prize in Physics, Collège de France.
Khaled Toukan, Director of the Synchrotron-light for Experimental Science and Applications in the Middle East (SESAME) based in Allan, Jordan.
The programme of keynotes and roundtables will address many key issues including science policy, our perception of the universe, and international cooperation, through contributions from experts and scientists from around the world.
The programme also includes cultural events, an illumination of UNESCO Headquarters, a photonics science show and an exhibit on the advances of light-based technologies and art.
The debates that flourished in 2015, in the framework of the International Year of Light, highlighted the importance of light sciences and light-based technologies in achieving the United Nations Sustainable Development Goals. Several thousand events were held in 147 countries during the Year placed under the auspices of UNESCO.
The proclamation of 16 May as the International Day of Light was supported by UNESCO’s Executive Board following a proposal by Ghana, Mexico, New Zealand and the Russian Federation, and approved by the UNESCO General Conference in November 2017.
I have taken a look at the programme which is pretty interesting. Unfortunately, I can’t excerpt parts of it for inclusion here as very odd things happen when I attempt to ‘copy and paste’. On the plus side. there’s a bit more information about this ‘new day’ on its event page,
Light plays a central role in our lives. On the most fundamental level, through photosynthesis, light is at the origin of life itself. The study of light has led to promising alternative energy sources, lifesaving medical advances in diagnostics technology and treatments, light-speed internet and many other discoveries that have revolutionized society and shaped our understanding of the universe. These technologies were developed through centuries of fundamental research on the properties of light – starting with Ibn Al-Haytham’s seminal work, Kitab al-Manazir (Book of Optics), published in 1015 and including Einstein’s work at the beginning of the 20th century, which changed the way we think about time and light.
The International Day of Light celebrates the role light plays in science, culture and art, education, and sustainable development, and in fields as diverse as medicine, communications, and energy. The will allow many different sectors of society worldwide to participate in activities that demonstrates how science, technology, art and culture can help achieve the goals of UNESCO – building the foundation for peaceful societies.
The International Day of Light is celebrated on 16 May each year, the anniversary of the first successful operation of the laser in 1960 by physicist and engineer, Theodore Maiman. This day is a call to strengthen scientific cooperation and harness its potential to foster peace and sustainable development.
Happy International Day of Light on Wednesday, May 16, 2018!
Researcher Bor-Kai Hsiung’s work has graced this blog before but the topic was tarantulas and their structural colour. This time, it’s all about Australian peacock spiders and their structural colour according to a December 22, 2017 news item on ScienceDaily,
Even if you are arachnophobic, you probably have seen pictures or videos of Australian peacock spiders (Maratus spp.). These tiny spiders are only 1-5 mm long but are famous for their flamboyant courtship displays featuring diverse and intricate body colorations, patterns, and movements.
The spiders extremely large anterior median eyes have excellent color vision and combine with their bright colors to make peacock spiders cute enough to cure most people of their arachnophobia. But these displays aren’t just pretty to look at, they also inspire new ways for humans to produce color in technology.
One species of peacock spider — the rainbow peacock spider (Maratus robinsoni) is particularly neat, because it showcases an intense rainbow iridescent signal in males’ courtship displays to the females. This is the first known instance in nature of males using an entire rainbow of colors to entice females. Dr. Bor-Kai Hsiung led an international team of researchers from the US (UAkron, Cal Tech, UC San Diego, UNL [University of Nebraska-Lincoln]), Belgium (Ghent University), Netherlands (UGroningen), and Australia to discover how rainbow peacock spiders produce this unique multi-color iridescent signal.
Using a diverse array of research techniques, including light and electron microscopy, hyperspectral imaging, imaging scatterometry, nano 3D printing and optical modeling, the team found the origin of this intense rainbow iridescence emerged from specialized abdominal scales of the spiders. These scales have an airfoil-like microscopic 3D contour with nanoscale diffraction grating structures on the surface.
The interaction between the surface nano-diffraction grating and the microscopic curvature of the scales enables separation and isolation of light into its component wavelengths at finer angles and smaller distances than are possible with current manmade engineering technologies.
Inspiration from these super iridescent scales can be used to overcome current limitations in spectral manipulation, and to further reduce the size of optical spectrometers for applications where fine-scale spectral resolution is required in a very small package, notably instruments on space missions, or wearable chemical detection systems. And it could have a wide array of implications to fields ranging from life sciences and biotechnologies to material sciences and engineering.
Here’s a video of an Australian rainbow peacock spider,
Here’s more from the YouTube description published on April 13, 2017 by Peacockspiderman,
Scenes of Maratus robinsoni, a spider Peter Robinson discovered and David Hill and I named it after him in 2012. You can read our description on pages 36-41 in Peckhamia 103.2, which can be downloaded from the Peckhamia website http://peckhamia.com/peckhamia_number…. This is one of the two smallest species of peacock spider (2.5 mm long) and the only spider we know of in which colour changes occur every time it moves, this video was created to document this. Music: ‘Be Still’ by Johannes Bornlöf licensed through my MCN ‘Brave Bison’ from ‘Epidemic Sound’ For licensing inquiries please contact Brave Bison email@example.com
The University of California at San Diego also published a December 22, 2017 news release about this work, which covers some of the same ground while providing a few new tidbits of information,
Brightly colored Australian peacock spiders (Maratus spp.) captivate even the most arachnophobic viewers with their flamboyant courtship displays featuring diverse and intricate body colorations, patterns, and movements – all packed into miniature bodies measuring less than five millimeters in size for many species. However, these displays are not just pretty to look at. They also inspire new ways for humans to produce color in technology.
One species of peacock spider – the rainbow peacock spider (Maratus robinsoni) – is particularly impressive, because it showcases an intense rainbow iridescent signal in males’ courtship displays to females. This is the first known instance in nature of males using an entire rainbow of colors to entice females to mate. But how do males make their rainbows? A new study published in Nature Communications looked to answer that question.
Figuring out the answers was inherently interdisciplinary so Bor-Kai Hsiung, a postdoctoral scholar at Scripps Institution of Oceanography at the University of California San Diego, assembled an international team that included biologists, physicists and engineers. Starting while he was a Ph.D. student at The University of Akron under the mentorship of Todd Blackledge and Matthew Shawkey, the team included researchers from UA, Scripps Oceanography, California Institute of Technology, and University of Nebraska-Lincoln, the University of Ghent in Belgium, University of Groningen in Netherlands, and Australia to discover how rainbow peacock spiders produce this unique iridescent signal.
The team investigated the spider’s photonic structures using techniques that included light and electron microscopy, hyperspectral imaging, imaging scatterometry and optical modeling to generate hypotheses about how the spider’s scale generate such intense rainbows. The team then used cutting-edge nano 3D printing to fabricate different prototypes to test and validate their hypotheses. In the end, they found that the intense rainbow iridescence emerged from specialized abdominal scales on the spiders. These scales combine an airfoil-like microscopic 3D contour with nanoscale diffraction grating structures on the surface. It is the interaction between the surface nano-diffraction grating and the microscopic curvature of the scales that enables separation and isolation of light into its component wavelengths at finer angles and smaller distances than are possible with current engineering technologies.
“Who knew that such a small critter would create such an intense iridescence using extremely sophisticated mechanisms that will inspire optical engineers,” said Dimitri Deheyn, Hsuing’s advisor at Scripps Oceanography and a coauthor of the study.
For Hsiung, the finding wasn’t quite so unexpected.
“One of the main questions that I wanted to address in my Ph.D. dissertation was ‘how does nature modulate iridescence?’ From a biomimicry perspective, to fully understand and address a question, one has to take extremes from both ends into consideration. I purposefully chose to study these tiny spiders with intense iridescence after having investigated the non-iridescent blue tarantulas,” said Hsiung.
The mechanism behind these tiny rainbows may inspire new color technology, but would not have been discovered without research combining basic natural history with physics and engineering, the researchers said.
“Nanoscale 3D printing allowed us to experimentally validate our models, which was really exciting,” said Shawkey. “We hope that these techniques will become common in the future.”
“As an engineer, what I found fascinating about these spider structural colors is how these long evolved complex structures can still outperform human engineering,” said Radwanul Hasan Siddique, a postdoctoral scholar at Caltech and study coauthor. “Even with high-end fabrication techniques, we could not replicate the exact structures. I wonder how the spiders assemble these fancy structural patterns in the first place!”
Inspiration from these super iridescent spider scales can be used to overcome current limitations in spectral manipulation, and to reduce the size of optical spectrometers for applications where fine-scale spectral resolution is required in a very small package, notably instruments on space missions, or wearable chemical detection systems.
In the end, peacock spiders don’t just produce nature’s smallest rainbows.They could also have implications for a wide array of fields ranging from life sciences and biotechnologies to material sciences and engineering.
Before citing the paper and providing a link, here’s a story by Robert F. Service for Science magazine about attempts to capitalize on ‘spider technology’, in this case spider silk,
The hype over spider silk has been building since 1710. That was the year François Xavier Bon de Saint Hilaire, president of the Royal Society of Sciences in Montpellier, France, wrote to his colleagues, “You will be surpriz’d to hear, that Spiders make a Silk, as beautiful, strong and glossy, as common Silk.” Modern pitches boast that spider silk is five times stronger than steel yet more flexible than rubber. If it could be made into ropes, a macroscale web would be able to snare a jetliner.
The key word is “if.” Researchers first cloned a spider silk gene in 1990, in hopes of incorporating it into other organisms to produce the silk. (Spiders can’t be farmed like silkworms because they are territorial and cannibalistic.) Today, Escherichia coli bacteria, yeasts, plants, silkworms, and even goats have been genetically engineered to churn out spider silk proteins, though the proteins are often shorter and simpler than the spiders’ own. Companies have managed to spin those proteins into enough high-strength thread to produce a few prototype garments, including a running shoe by Adidas and a lightweight parka by The North Face. But so far, companies have struggled to mass produce these supersilks.
Some executives say that may finally be about to change. One Emeryville, California-based startup, Bolt Threads, says it has perfected growing spider silk proteins in yeast and is poised to turn out tons of spider silk thread per year. In Lansing, Michigan, Kraig Biocraft Laboratories says it needs only to finalize negotiations with silkworm farms in Vietnam to produce mass quantities of a combination spider/silkworm silk, which the U.S. Army is now testing for ballistics protection. …
I encourage you to read Service’s article in its entirety if the commercialization prospects for spider silk interest you as it includes gems such as this,
Spider silk proteins are already making their retail debut—but in cosmetics and medical devices, not high-strength fibers. AMSilk grows spider silk proteins in E. coli and dries the purified protein into powders or mixes it into gels, for use as additives for personal care products, such as moisture-retaining skin lotions. The silk proteins supposedly help the lotions form a very smooth, but breathable, layer over the skin. Römer says the company now sells tons of its purified silk protein ingredients every year.
Finally, here’s a citation for and a link to the paper about Australian peacock spiders and nanophotonics,
Rainbow peacock spiders inspire miniature super-iridescent optics by Bor-Kai Hsiung, Radwanul Hasan Siddique, Doekele G. Stavenga, Jürgen C. Otto, Michael C. Allen, Ying Liu, Yong-Feng Lu, Dimitri D. Deheyn, Matthew D. Shawkey, & Todd A. Blackledge. Nature Communications 8, Article number: 2278 (2017) doi:10.1038/s41467-017-02451-x Published online: 22 December 2017
Colors are produced in a variety of ways. The best known colors are pigments. However, the very bright colors of the blue tarantula or peacock feathers do not result from pigments, but from nanostructures that cause the reflected light waves to overlap. This produces extraordinarily dynamic color effects. Scientists from Karlsruhe Institute of Technology (KIT), in cooperation with international colleagues, have now succeeded in replicating nanostructures that generate the same color irrespective of the viewing angle. DOI: 10.1002/adom.201600599
In contrast to pigments, structural colors are non-toxic, more vibrant and durable. In industrial production, however, they have the drawback of being strongly iridescent, which means that the color perceived depends on the viewing angle. An example is the rear side of a CD. Hence, such colors cannot be used for all applications. Bright colors of animals, by contrast, are often independent of the angle of view. Feathers of the kingfisher always appear blue, no matter from which angle we look. The reason lies in the nanostructures: While regular structures are iridescent, amorphous or irregular structures always produce the same color. Yet, industry can only produce regular nanostructures in an economically efficient way.
Radwanul Hasan Siddique, researcher at KIT in collaboration with scientists from USA and Belgium has now discovered that the blue tarantula does not exhibit iridescence in spite of periodic structures on its hairs. First, their study revealed that the hairs are multi-layered, flower-like structure. Then, the researchers analyzed its reflection behavior with the help of computer simulations. In parallel, they built models of these structures using nano-3D printers and optimized the models with the help of the simulations. In the end, they produced a flower-like structure that generates the same color over a viewing angle of 160 degrees. This is the largest viewing angle of any synthetic structural color reached so far.
Flower-shaped nanostructures generate the color of the blue tarantula. (Graphics: Bill Hsiung, University of Akron)
The 3D print of the optimized flower structure is only 15 µm in dimension. A human hair is about three times as thick. (Photo: Bill Hsiung, Universtiy of Akron)
Apart from the multi-layered structure and rotational symmetry, it is the hierarchical structure from micro to nano that ensures homogeneous reflection intensity and prevents color changes.
Via the size of the “flower,” the resulting color can be adjusted, which makes this coloring method interesting for industry. “This could be a key first step towards a future where structural colorants replace the toxic pigments currently used in textile, packaging, and cosmetic industries,” says Radwanul Hasan Siddique of KIT’s Institute of Microstructure Technology, who now works at the California Institute of Technology. He considers short-term application in textile industry feasible.
The synthetically generated flower structure inspired by the blue tarantula reflects light in the same color over a viewing angle of 160 degrees. (Graphics: Derek Miller)
Dr. Hendrik Hölscher thinks that the scalability of nano-3D printing is the biggest challenge on the way towards industrial use. Only few companies in the world are able to produce such prints. In his opinion, however, rapid development in this field will certainly solve this problem in the near future.
Once again, here’s a link to and a citation for the paper,
Biohybrid robots, as they are known, are built from living tissue but not in a Frankenstein kind of way as Victoria Webster PhD candidate at Case Western Reserve University (US) explains in her Aug. 9, 2016 essay on The Conversation (also on phys.org as an Aug. 10, 2016 news item; Note: Links have been removed),
Researchers are increasingly looking for solutions to make robots softer or more compliant – less like rigid machines, more like animals. With traditional actuators – such as motors – this can mean using air muscles or adding springs in parallel with motors. …
But there’s a growing area of research that’s taking a different approach. By combining robotics with tissue engineering, we’re starting to build robots powered by living muscle tissue or cells. These devices can be stimulated electrically or with light to make the cells contract to bend their skeletons, causing the robot to swim or crawl. The resulting biobots can move around and are soft like animals. They’re safer around people and typically less harmful to the environment they work in than a traditional robot might be. And since, like animals, they need nutrients to power their muscles, not batteries, biohybrid robots tend to be lighter too.
Webster explains how these biobots are built,
Researchers fabricate biobots by growing living cells, usually from heart or skeletal muscle of rats or chickens, on scaffolds that are nontoxic to the cells. If the substrate is a polymer, the device created is a biohybrid robot – a hybrid between natural and human-made materials.
If you just place cells on a molded skeleton without any guidance, they wind up in random orientations. That means when researchers apply electricity to make them move, the cells’ contraction forces will be applied in all directions, making the device inefficient at best.
So to better harness the cells’ power, researchers turn to micropatterning. We stamp or print microscale lines on the skeleton made of substances that the cells prefer to attach to. These lines guide the cells so that as they grow, they align along the printed pattern. With the cells all lined up, researchers can direct how their contraction force is applied to the substrate. So rather than just a mess of firing cells, they can all work in unison to move a leg or fin of the device.
Researchers sometimes mimic animals when creating their biobots (Note: Links have been removed),
Others have taken their cues from nature, creating biologically inspired biohybrids. For example, a group led by researchers at California Institute of Technology developed a biohybrid robot inspired by jellyfish. This device, which they call a medusoid, has arms arranged in a circle. Each arm is micropatterned with protein lines so that cells grow in patterns similar to the muscles in a living jellyfish. When the cells contract, the arms bend inwards, propelling the biohybrid robot forward in nutrient-rich liquid.
More recently, researchers have demonstrated how to steer their biohybrid creations. A group at Harvard used genetically modified heart cells to make a biologically inspired manta ray-shaped robot swim. The heart cells were altered to contract in response to specific frequencies of light – one side of the ray had cells that would respond to one frequency, the other side’s cells responded to another.
Amazing, eh? And, this is quite a recent video; it was published on YouTube on July 7, 2016.
Webster goes on to describe work designed to make these robots hardier and more durable so they can leave the laboratory,
… Here at Case Western Reserve University, we’ve recently begun to investigate … by turning to the hardy marine sea slug Aplysia californica. Since A. californica lives in the intertidal region, it can experience big changes in temperature and environmental salinity over the course of a day. When the tide goes out, the sea slugs can get trapped in tide pools. As the sun beats down, water can evaporate and the temperature will rise. Conversely in the event of rain, the saltiness of the surrounding water can decrease. When the tide eventually comes in, the sea slugs are freed from the tidal pools. Sea slugs have evolved very hardy cells to endure this changeable habitat.
We’ve been able to use Aplysia tissue to actuate a biohybrid robot, suggesting that we can manufacture tougher biobots using these resilient tissues. The devices are large enough to carry a small payload – approximately 1.5 inches long and one inch wide.
Webster has written a fascinating piece and, if you have time, I encourage you to read it in its entirety.
This glowing reproduction of “The Starry Night” contains 65,536 pixels and is the width of a dime across. Credit: Ashwin Gopinath/Caltech
It may take you a few seconds (it did me) but it’s possible to see Van Gogh’s Starry Night in this image. A July 12, 2016 news item on ScienceDaily reveals more,
Using folded DNA [deoxyribonucleic acid] to precisely place glowing molecules within microscopic light resonators, researchers at Caltech have created one of the world’s smallest reproductions of Vincent van Gogh’s The Starry Night.
A July 12, 2016 Caltech news release (also on EurekAlert) by Richard Perkins, which originated the news item, provides more information about the image, DNA origami, and this latest research on coupling light emitters to photonic crystal cavities (Note: Links have been removed),
The monochrome image—just the width of a dime across—was a proof-of-concept project that demonstrated, for the first time, how the precision placement of DNA origami can be used to build chip-based devices like computer circuits at smaller scales than ever before.
DNA origami, developed 10 years ago by Caltech’s Paul Rothemund (BS ’94), is a technique that allows researchers to fold a long strand of DNA into any desired shape. The folded DNA then acts as a scaffold onto which researchers can attach and organize all kinds of nanometer-scale components, from fluorescent molecules to electrically conductive carbon nanotubes to drugs.
“Think of it a bit like the pegboards people use to organize tools in their garages, only in this case, the pegboard assembles itself from DNA strands and the tools likewise find their own positions,” says Rothemund, research professor of bioengineering, computing and mathematical sciences, and computation and neural systems. “It all happens in a test tube without human intervention, which is important because all of the parts are too small to manipulate efficiently, and we want to make billions of devices.”
The process has the potential to influence a variety of applications from drug delivery to the construction of nanoscale computers. But for many applications, organizing nanoscale components to create devices on DNA pegboards is not enough; the devices have to be wired together into larger circuits and need to have a way of communicating with larger-scale devices.
One early approach was to make electrodes first, and then scatter devices randomly on a surface, with the expectation that at least a few would land where desired, a method Rothemund describes as “spray and pray.”
In 2009, Rothemund and colleagues at IBM Research first described a technique through which DNA origami can be positioned at precise locations on surfaces using electron-beam lithography to etch sticky binding sites that have the same shape as the origami. For example, triangular sticky patches bind triangularly folded DNA.
Over the last seven years, Rothemund and Ashwin Gopinath, senior postdoctoral scholar in bioengineering at Caltech, have refined and extended this technique so that DNA shapes can be precisely positioned on almost any surface used in the manufacture of computer chips. In the Nature paper, they report the first application of the technique—using DNA origami to install fluorescent molecules into microscopic light sources.
“It’s like using DNA origami to screw molecular light bulbs into microscopic lamps,” Rothemund says.
In this case, the lamps are microfabricated structures called photonic crystal cavities (PCCs), which are tuned to resonate at a particular wavelength of light, much like a tuning fork vibrates with a particular pitch. Created within a thin glass-like membrane, a PCC takes the form of a bacterium-shaped defect within an otherwise perfect honeycomb of holes.
“Depending on the exact size and spacing of the holes, a particular wavelength of light reflects off the edge of the cavity and gets trapped inside,” says Gopinath, the lead author of the study. He built PCCs that are tuned to resonate at around 660 nanometers, the wavelength corresponding to a deep shade of the color red. Fluorescent molecules tuned to glow at a similar wavelength light up the lamps—provided they stick to exactly the right place within the PCC.
“A fluorescent molecule tuned to the same color as a PCC actually glows more brightly inside the cavity, but the strength of this coupling effect depends strongly on the molecule’s position within the cavity. A few tens of nanometers is the difference between the molecule glowing brightly, or not at all,” Gopinath says.
By moving DNA origami through the PCCs in 20-nanometer steps, the researchers found that they could map out a checkerboard pattern of hot and cold spots, where the molecular light bulbs either glowed weakly or strongly. As a result, they were able to use DNA origami to position fluorescent molecules to make lamps of varying intensity. Similar structures have been proposed to power quantum computers and for use in other optical applications that require many tiny light sources integrated together on a single chip.
“All previous work coupling light emitters to PCCs only successfully created a handful of working lamps, owing to the extraordinary difficulty of reproducibly controlling the number and position of emitters in a cavity,” Gopinath says. To prove their new technology, the researchers decided to scale-up and provide a visually compelling demonstration. By creating PCCs with different numbers of binding sites, Gopinath was able to reliably install any number from zero to seven DNA origami, allowing him to digitally control the brightness of each lamp. He treated each lamp as a pixel with one of eight different intensities, and produced an array of 65,536 of the PCC pixels (a 256 x 256 pixel grid) to create a reproduction of Van Gogh’s “The Starry Night.”
Now that the team can reliably combine molecules with PCCs, they are working to improve the light emitters. Currently, the fluorescent molecules last about 45 seconds before reacting with oxygen and “burning out,” and they emit a few shades of red rather than a single pure color. Solving both these problems will help with applications such as quantum computers.
“Aside from applications, there’s a lot of fundamental science to be done,” Gopinath says.
There are two upcoming science events in Vancouver.
*Cancellation notice received via email March 29, 2016 at 1430 hours PDT:
Our sincerest apologies, but we have just received word that The Railway Club is shutting it’s doors for good, effective immediately. Unfortunately, because of this tonight’s event is cancelled. We will do our best to re-schedule the talk in the near future once we have found a new venue.
The Tues., March 29, 2016 (tonight) Café Scientifique talk at 7:30 pm, Café Scientifique, in the back room of The Railway Club (2nd floor of 579 Dunsmuir St. [at Seymour St.]), has one of the more peculiar descriptions for a talk that I’ve seen for this group. From a March 1, 2016 announcement (received via e-mail),
Our speaker for the evening will be Dr. Jerilynn Prior. Prior is Professor of Endocrinology and Metabolism at the University of British Columbia, founder and scientific director of the Centre for Menstrual Cycle and Ovulation Research (CeMCOR), director of the BC Center of the Canadian Multicenter Osteoporosis Study (CaMOS), and a past president of the Society for Menstrual Cycle Research. The title of her talk is:
Is Perimenopause Estrogen Deficiency?
Sorting engrained misinformation about women’s midlife reproductive transition
43 years old with teenagers a full-time executive director of a not for profit is not sleeping, she wakes soaked a couple of times a night, not every night but especially around the time her period comes. As it does frequently—it is heavy, even flooding. Her sexual interest is virtually gone and she feels dry when she tries.
Her family doctor offered her The Pill. When she took it she got very sore breasts, ankle swelling and high blood pressure. Her brain feels fuzzy, she’s getting migraines, gaining weight and just can’t cope. . . .
What’s going on? Does she need estrogen “replacement”? If yes, why when she’s still getting flow? Does The Pill work for other women? What do we know about the what, why, how long and how to help symptomatic perimenopausal women?
This description seems more appropriate for a workshop on women’s health for doctors and/or women going through ‘the change’.
We invite you to join us for an evening with renowned theoretical physicist Kip Thorne.
100 years ago, Albert Einstein formulated his wildly successful general theory of relativity—a set of physical laws that attribute gravity to the warping of time and space. It has been tested with high precision in the solar system and in binary pulsars and explains the expansion of the universe. It even predicts black holes and gravitational waves. When combined with quantum theory, relativity provides a tentative framework for understanding the universe’s big-bang birth. And the equations that made Einstein famous have become embedded in our popular culture via, for example, the science fiction movie Interstellar.
In a captivating talk accessible to science enthusiasts of all ages, Professor Kip Thorne will use Interstellar to illustrate some of relativity’s deepest ideas, including black holes and the recent discovery of gravitational waves.
Professor Thorne of the California Institute of Technology is one of the world’s foremost experts on the astrophysics implications of Einstein’s General Theory of Relativity, including black holes—an expertise he used to great effect as scientific advisor to the movieInterstellar. Thorne was also one of the three principal scientists (with Rainer Weiss and Ron Drever) behind the LIGO experiment that recently detected gravitational waves, an achievement most expect will earn them a Nobel Prize.
This event is organized by Science World, TRIUMF, and the UBC Department of Physics & Astronomy. It is part of UBC’s Centennial Celebration.
Sadly, I did not receive details and a link for registration in a more timely fashion although I was able to give readers a heads-up in a Jan. 22, 2016 posting. (scroll down about 25% of the way down).