Category Archives: biomimcry

Inspiration from the sea for titanium implants (mussels) and adhesive panels for flexible sensors (octopuses/octopi/octopodes)

I have two sea-inspired news bits both of which concern adhesion.

Mussels and titanium implants

A July 8, 2016 news item on ScienceDaily features some mussel-inspired research from Japan into how to make better titanium implants,

Titanium is used medically in applications such as artificial joints and dental implants. While it is strong and is not harmful to tissues, the metal lacks some of the beneficial biological properties of natural tissues such as bones and natural teeth. Now, based on insights from mussels–which are able to attach themselves very tightly to even metallic surfaces due to special proteins found in their byssal threads–scientists from RIKEN have successfully attached a biologically active molecule to a titanium surface, paving the way for implants that can be more biologically beneficial.

A July 11, 2016 RIKEN press release (also on EurekAlert but dated July 8, 2016), which originated the news item, provides more information,

The work began from earlier discoveries that mussels can attach to smooth surfaces so effectively thanks to a protein, L-DOPA, which is known to be able to bind very strongly to smooth surfaces such as rocks, ceramics, or metals (…). Interestingly, the same protein functions in humans as a precursor to dopamine, and is used as a treatment for Parkinson’s disease.

According to Chen Zhang of the RIKEN Nano Medical Engineering Laboratory, the first author of the paper published in Angewandte Chemie, “We thought it would be interesting to try to use various techniques to attach a biologically active protein—in our case we chose insulin-like growth factor-1, a promoter of cell proliferation—to a titanium surface like those used in implants” (…).

Using a combination of recombinant DNA technology and treatment with tyrosinase, they were able to create a hybrid protein that contained active parts of both the growth factor and L-DOPA. Tests showed that the proteins were able to fold normally, and further experiments in cell cultures demonstrated that the IGF-1 was still functioning normally. Thanks to the incorporation of the L-DOPA, the team was able to confirm that the proteins bound strongly to the titanium surface, and remained attached even when the metal was washed with phosphate-buffered saline, a water-based solution. Zhang says, “This is similar to the powerful properties of mussel adhesive, which can remain fixed to metallic materials even underwater.”

According to Yoshihiro Ito, Team Leader of the Emergent Bioengineering Research Team of the RIKEN Center for Emergent Matter Science, “We are very excited by this finding, because the modification process is a universal one that could be used with other proteins. It could allow us to prepare new cell-growth enhancing materials, with potential applications in cell culture systems and regenerative medicine. And it is particularly interesting that this is an example of biomimetics, where nature can teach us new ways to do things. The mussel has given us insights that could be used to allow us to live healthier lives.”

The work was done by RIKEN researchers in collaboration with Professor Peibiao Zhang of the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, and Professor Yi Wang of the School of Pharmaceutical Sciences, Jilin University. The work was partially supported by the Japan Society for the Promotion of Science KAKENHI (Grant Number 15H01810 and 22220009), CAS-JSPS joint fund (GJHZ1519), and RIKEN MOST joint project.

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

A Bioorthogonal Approach for the Preparation of a Titanium-Binding Insulin-like Growth-Factor-1 Derivative by using Tyrosinase by Chen Zhang, Hideyuki Miyatake, Yu Wang, Takehiko Inaba, Yi Wang, Peibiao Zhang, and Prof. Yoshihiro Ito. Angewandte Chemie International Edition DOI: 10.1002/anie.201603155 Version of Record online: 6 JUL 2016

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

This paper is behind a paywall.

Octopuses/octopi/octopodes and adhesive panels

Before launching into the science part of this news bit, here’s some grammar (from the Octopus Wikipedia entry; Note: Links have been removed),

The standard pluralized form of “octopus” in the English language is “octopuses” /ˈɒktəpʊsɪz/,[10] although the Ancient Greek plural “octopodes” /ɒkˈtɒpədiːz/, has also been used historically.[9] The alternative plural “octopi” — which misguidedly assumes it is a Latin “-us”-word — is considered grammatically incorrect.[11][12][13][14] It is nevertheless used enough to make it notable, and was formally acknowledged by the descriptivist Merriam-Webster 11th Collegiate Dictionary and Webster’s New World College Dictionary. The Oxford English Dictionary (2008 Draft Revision)[15] lists “octopuses”, “octopi”, and “octopodes”, in that order, labelling “octopodes” as rare and noting that “octopi” derives from the apprehension that octōpus comes from Latin.[16] In contrast, New Oxford American Dictionary (3rd Edition 2010) lists “octopuses” as the only acceptable pluralization, with a usage note indicating “octopodes” as being still occasionally used but “octopi” as being incorrect.[17]

Now the news. A July 12, 2016 news item on Nanowerk highlights some research into adhesives and octopuses,

With increased study of bio-adhesives, a significant effort has been made in search for novel adhesives that will combine reversibility, repeated usage, stronger bonds and faster bonding time, non-toxic, and more importantly be effective in wet and other extreme conditions.

A team of Korean scientists-made up of scientists from Korea Institute of Science and Technology (KIST) and UNIST has recently found a way to make building flexible pressure sensors easier–by mimicking the suction cups on octopus’s tentacles.

A July 5, 2016 UNIST (Ulsan National Institute of Science and Technology) press release, which originated the news item, provides more information,

According to the research team, “Although flexible pressure sensors might give future prosthetics and robots a better sense of touch, building them requires a lot of laborious transferring of nano- and microribbons of inorganic semiconductor materials onto polymer sheets.”

In search of an easier way to process this transfer printing, Prof. Hyunhyub Ko (School of Energy and Chemical Engineering, UNIST) and his colleagues turned to the octopus suction cups for inspiration.

An octopus uses its tentacles to move to a new location and uses suction cups underneath each tentacle to grab onto something. Each suction cup contains a cavity whose pressure is controlled by surrounding muscles. These can be made thinner or thicker on demand, increasing or decreasing air pressure inside the cup, allowing for sucking and releasing as desired.

By mimicking muscle actuation to control cavity-pressure-induced adhesion of octopus suckers, Prof. Ko and his team engineered octopus-inspired smart adhesive pads. They used the rubbery material polydimethylsiloxane (PDMS) to create an array of microscale suckers, which included pores that are coated with a thermally responsive polymer to create sucker-like walls.

The team discovered that the best way to replicate organic nature of muscle contractions would be through applied heat. Indeed, at room temperature, the walls of each pit sit in an ‘open’ state, but when the mat is heated to 32°C, the walls contract, creating suction, therby allowing the entire mate to adhere to a material (mimicking the suction function of an octopus). The adhesive strength also spiked from .32 kilopascals to 94 kilopascals at high temperature.

The team reports that the mat worked as envisioned—they made some indium gallium arsenide transistors that sat on a flexible substrate and also used it to move some nanomaterials to a different type of flexible material.

Prof. Ko and his team expect that their smart adhesive pads can be used as the substrate for wearable health sensors, such as Band-Aids or sensors that stick to the skin at normal body temperatures but fall off when rinsed under cold water.

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

Octopus-Inspired Smart Adhesive Pads for Transfer Printing of Semiconducting Nanomembranes by Hochan Lee, Doo-Seung Um, Youngsu Lee, Seongdong Lim, Hyung-jun Kim,  and Hyunhyub Ko. Advanced Materials DOI: 10.1002/adma.201601407 Version of Record online: 20 JUN 2016

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

This paper is behind a paywall.

Photovoltaics as rose petals

Where solar cells (photovoltaics) are concerned, mimimicking plants is a longstanding pursuit. The latest  plant material to be mimicked is the rose petal’s surface. From a June 24, 2016 news item on ScienceDaily,

With a surface resembling that of plants, solar cells improve light-harvesting and thus generate more power. Scientists of KIT (Karlsruhe Institute of Technology) reproduced the epidermal cells of rose petals that have particularly good antireflection properties and integrated the transparent replicas into an organic solar cell. This resulted in a relative efficiency gain of twelve percent. …

Caption: Biomimetics: the epidermis of a rose petal is replicated in a transparent layer which is then integrated into the front of a solar cell. Credit Illustration: Guillaume Gomard, KIT

Caption: Biomimetics: the epidermis of a rose petal is replicated in a transparent layer which is then integrated into the front of a solar cell.
Credit Illustration: Guillaume Gomard, KIT

A June 24, 2016 KIT press release on EurekAlert, which originated the news item, expands on the theme,

Photovoltaics works in a similar way as the photosynthesis of plants. Light energy is absorbed and converted into a different form of energy. In this process, it is important to use a possibly large portion of the sun’s light spectrum and to trap the light from various incidence angles as the angle changes with the sun’s position. Plants have this capability as a result of a long evolution process – reason enough for photovoltaics researchers to look closely at nature when developing solar cells with a broad absorption spectrum and a high incidence angle tolerance.

Scientists at the KIT and the ZSW (Center for Solar Energy and Hydrogen Research Baden-Württemberg) now suggest in their article published in the Advanced Optical Materials journal to replicate the outermost tissue of the petals of higher plants, the so-called epidermis, in a transparent layer and integrate that layer into the front of solar cells in order to increase their efficiency.

First, the researchers at the Light Technology Institute (LTI), the Institute of Microstructure Technology (IMT), the Institute of Applied Physics (APH), and the Zoological Institute (ZOO) of KIT as well as their colleagues from the ZSW investigated the optical properties, and above all, the antireflection effect of the epidermal cells of different plant species. These properties are particularly pronounced in rose petals where they provide stronger color contrasts and thus increase the chance of pollination. As the scientists found out under the electron microscope, the epidermis of rose petals consists of a disorganized arrangement of densely packed microstructures, with additional ribs formed by randomly positioned nanostructures.

In order to exactly replicate the structure of these epidermal cells over a larger area, the scientists transferred it to a mold made of polydimethylsiloxane, a silicon-based polymer, pressed the resulting negative structure into optical glue which was finally left to cure under UV light. “This easy and cost-effective method creates microstructures of a depth and density that are hardly achievable with artificial techniques,” says Dr. Guillaume Gomard, Group Leader “Nanopothonics” at KIT’s LTI.

The scientists then integrated the transparent replica of the rose petal epidermis into an organic solar cell. This resulted in power conversion efficiency gains of twelve percent for vertically incident light. At very shallow incidence angles, the efficiency gain was even higher. The scientists attribute this gain primarily to the excellent omnidirectional antireflection properties of the replicated epidermis that is able to reduce surface reflection to a value below five percent, even for a light incidence angle of nearly 80 degrees. In addition, as examinations using a confocal laser microscope showed, every single replicated epidermal cell works as a microlense. The microlense effect extends the optical path within the solar cell, enhances the light-matter-interaction, and increases the probability that the photons will be absorbed.

“Our method is applicable to both other plant species and other PV technologies,” Guillaume Gomard explains. “Since the surfaces of plants have multifunctional properties, it might be possible in the future to apply multiple of these properties in a single step.” The results of this research lead to another basic question: What is the role of disorganization in complex photonic structures? Further studies are now examining this issue with the perspective that the next generation of solar cells might benefit from their results.

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

Flower Power: Exploiting Plants’ Epidermal Structures for Enhanced Light Harvesting in Thin-Film Solar Cells by Ruben Hünig, Adrian Mertens, Moritz Stephan, Alexander Schulz, Benjamin Richter, Michael Hetterich, Michael Powalla, Uli Lemmer, Alexander Colsmann, and Guillaume Gomard. Advanced Optical Materials  Version of Record online: 30 MAY 2016 DOI: 10.1002/adom.201600046

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

This paper is behind a paywall.

Squeezing out ‘polymer opals’ for smart clothing and more

Researchers at the University of Cambridge have developed a technology for producing ‘polymer opals’ on industrial scales according to a June 3, 2016 news item on Nanowerk (Note: A link has been removed),

Using a new method called Bend-Induced-Oscillatory-Shearing (BIOS), the researchers are now able to produce hundreds of metres of these materials, known as ‘polymer opals’, on a roll-to-roll process. The results are reported in the journal Nature Communications (“Large-scale ordering of nanoparticles using viscoelastic shear processing”).

A June 3, 2016 University of Cambridge press release (also on EurekAlert), which originated the news item, provides more detail (Note: Links have been removed),

Researchers have devised a new method for stacking microscopic marbles into regular layers, producing intriguing materials which scatter light into intense colours, and which change colour when twisted or stretched.

Some of the brightest colours in nature can be found in opal gemstones, butterfly wings and beetles. These materials get their colour not from dyes or pigments, but from the systematically-ordered microstructures they contain.

The team behind the current research, based at Cambridge’s Cavendish Laboratory, have been working on methods of artificially recreating this ‘structural colour’ for several years, but to date, it has been difficult to make these materials using techniques that are cheap enough to allow their widespread use.

In order to make the polymer opals, the team starts by growing vats of transparent plastic nano-spheres. Each tiny sphere is solid in the middle but sticky on the outside. The spheres are then dried out into a congealed mass. By bending sheets containing a sandwich of these spheres around successive rollers the balls are magically forced into perfectly arranged stacks, by which stage they have intense colour.

By changing the sizes of the starting nano-spheres, different colours (or wavelengths) of light are reflected. And since the material has a rubber-like consistency, when it is twisted and stretched, the spacing between the spheres changes, causing the material to change colour. When stretched, the material shifts into the blue range of the spectrum, and when compressed, the colour shifts towards red. When released, the material returns to its original colour. Such chameleon materials could find their way into colour-changing wallpapers, or building coatings that reflect away infrared thermal radiation.

I always like it when there are quotes which seem spontaneous (from the press release),

“Finding a way to coax objects a billionth of a metre across into perfect formation over kilometre scales is a miracle [emphasis mine],” said Professor Jeremy Baumberg, the paper’s senior author. “But spheres are only the first step, as it should be applicable to more complex architectures on tiny scales.”

In order to make polymer opals in large quantities, the team first needed to understand their internal structure so that it could be replicated. Using a variety of techniques, including electron microscopy, x-ray scattering, rheology and optical spectroscopy, the researchers were able to see the three-dimensional position of the spheres within the material, measure how the spheres slide past each other, and how the colours change.

“It’s wonderful [emphasis mine] to finally understand the secrets of these attractive films,” said PhD student Qibin Zhao, the paper’s lead author.

There’s also the commercialization aspect to this work (from the press release),

Cambridge Enterprise, the University’s commercialisation arm which is helping to commercialise the material, has been contacted by more than 100 companies interested in using polymer opals, and a new spin-out Phomera Technologies has been founded. Phomera will look at ways of scaling up production of polymer opals, as well as selling the material to potential buyers. Possible applications the company is considering include coatings for buildings to reflect heat, smart clothing and footwear, or for banknote security [emphasis mine] and packaging applications.

There is a Canadian company already selling its anti-counterfeiting (banknote security) bioinspired technology. It’s called Opalux and it’s not the only bioinspired anti-counterfeiting Canadian technology company, there’s also NanoTech Security which takes its inspiration from a butterfly (Blue Morpho) wing.

Getting back to Cambridge, here’s a link to and a citation for the research team’s paper,

Large-scale ordering of nanoparticles using viscoelastic shear processing by Qibin Zhao, Chris E. Finlayson, David R. E. Snoswell, Andrew Haines, Christian Schäfer, Peter Spahn, Goetz P. Hellmann, Andrei V. Petukhov, Lars Herrmann, Pierre Burdet, Paul A. Midgley, Simon Butler, Malcolm Mackley, Qixin Guo, & Jeremy J. Baumberg. Nature Communications 7, Article number: 11661  doi:10.1038/ncomms11661 Published 03 June 2016

This paper is open access.

There is a video demonstrating the stretchability of their ‘polymer opal’ film

It was posted on YouTube three years ago when the researchers were first successful. It’s nice to see they’ve been successful at getting the technology to the commercialization stage.

Green Hairstreak butterfly could make computer screens more brilliant

When talking about mimicking the nanostructures on butterfly wings, the butterfly in question is the Blue Morpho, usually. In a change of pace, researchers at Australia’s Swinburne University of Technology have focused their attention on the Green Hairstreak butterfly,

Nanostructures on the wings of the Callophrys Rubi or Green Hairstreak butterfly have inspired the design of an artificial material that could be used in photonics and optics technologies. Courtesy: Swinburne University of Technology

Nanostructures on the wings of the Callophrys Rubi or Green Hairstreak butterfly have inspired the design of an artificial material that could be used in photonics and optics technologies. Courtesy: Swinburne University of Technology

A June 1, 2016 Swinburne University of Technology press release describes the work,

Inspired by the intricate structure of a butterfly wing, Swinburne researchers have developed a technique that could be used to make more brilliant computer screens.

The researchers used a special printing technique to create tiny structures similar to those found in the wings of the Callophrys Rubi butterfly, also known as the Green Hairstreak.

In some iridescent butterfly wings, such as the Green Hairstreak, the wing is made up of a pattern of intertwining and curved surfaces, known as a gyroid structure.  This gyroid structure has amazing properties when it comes to its interactions with light.

The researchers used two-beams of light to print at a super-resolution, creating gyroid structures that are three-dimensional and mechanically strong.

Lead author Dr Zongsong Gan from Swinburne’s Centre for Micro-Photonics says that materials made from these artificial gyroids should respond to light at ultrafast speeds making them ideal for high-speed switches.

He says the technique has two significant advantages.

“The first is that it has improved resolution and the second is that the materials fabricated with this technique have better mechanical strength.

“These new gyroid structures could help make more compact light based electronics because, thanks to their smaller size, larger numbers of devices can be integrated onto a single chip.

“However, for three-dimensional devices, smaller and more compact also means there is a higher risk of structure collapse because of weaker mechanical strength.

“Our fabrication technique allows us to make stronger architectures to overcome this problem,” Dr Gan says.

Here’s an image illustrating the work,

Comparison of natural gyroid structure with artificial structure. Courtesy: Swinburne University of Technology

Comparison of natural gyroid structure with artificial structure. Courtesy: Swinburne University of Technology

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

Biomimetic gyroid nanostructures exceeding their natural origins by Zongsong Gan, Mark D. Turner, and Min Gu. Science Advances  13 May 2016: Vol. 2, no. 5, e1600084
DOI: 10.1126/sciadv.1600084

This appears to be an open access paper,

Making better concrete by looking to nature for inspiration

Researchers from the Masssachusetts Institute of Technology (MIT) are working on a new formula for concrete based on bones, shells, and other such natural materials. From a May 25, 2016 news item on Nanowerk (Note: A link has been removed),

Researchers at MIT are seeking to redesign concrete — the most widely used human-made material in the world — by following nature’s blueprints.

In a paper published online in the journal Construction and Building Materials (“Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach”), the team contrasts cement paste — concrete’s binding ingredient — with the structure and properties of natural materials such as bones, shells, and deep-sea sponges. As the researchers observed, these biological materials are exceptionally strong and durable, thanks in part to their precise assembly of structures at multiple length scales, from the molecular to the macro, or visible, level.

A May 26, 2016 MIT news release (also on EurekAlert), which originated the news item, provides more detail,

From their observations, the team, led by Oral Buyukozturk, a professor in MIT’s Department of Civil and Environmental Engineering (CEE), proposed a new bioinspired, “bottom-up” approach for designing cement paste.

“These materials are assembled in a fascinating fashion, with simple constituents arranging in complex geometric configurations that are beautiful to observe,” Buyukozturk says. “We want to see what kinds of micromechanisms exist within them that provide such superior properties, and how we can adopt a similar building-block-based approach for concrete.”

Ultimately, the team hopes to identify materials in nature that may be used as sustainable and longer-lasting alternatives to Portland cement, which requires a huge amount of energy to manufacture.

“If we can replace cement, partially or totally, with some other materials that may be readily and amply available in nature, we can meet our objectives for sustainability,” Buyukozturk says.

“The merger of theory, computation, new synthesis, and characterization methods have enabled a paradigm shift that will likely change the way we produce this ubiquitous material, forever,” Buehler says. “It could lead to more durable roads, bridges, structures, reduce the carbon and energy footprint, and even enable us to sequester carbon dioxide as the material is made. Implementing nanotechnology in concrete is one powerful example [of how] to scale up the power of nanoscience to solve grand engineering challenges.”

From molecules to bridges

Today’s concrete is a random assemblage of crushed rocks and stones, bound together by a cement paste. Concrete’s strength and durability depends partly on its internal structure and configuration of pores. For example, the more porous the material, the more vulnerable it is to cracking. However, there are no techniques available to precisely control concrete’s internal structure and overall properties.

“It’s mostly guesswork,” Buyukozturk says. “We want to change the culture and start controlling the material at the mesoscale.”

As Buyukozturk describes it, the “mesoscale” represents the connection between microscale structures and macroscale properties. For instance, how does cement’s microscopic arrangement affect the overall strength and durability of a tall building or a long bridge? Understanding this connection would help engineers identify features at various length scales that would improve concrete’s overall performance.

“We’re dealing with molecules on the one hand, and building a structure that’s on the order of kilometers in length on the other,” Buyukozturk says. “How do we connect the information we develop at the very small scale, to the information at the large scale? This is the riddle.”

Building from the bottom, up

To start to understand this connection, he and his colleagues looked to biological materials such as bone, deep sea sponges, and nacre (an inner shell layer of mollusks), which have all been studied extensively for their mechanical and microscopic properties. They looked through the scientific literature for information on each biomaterial, and compared their structures and behavior, at the nano-, micro-, and macroscales, with that of cement paste.

They looked for connections between a material’s structure and its mechanical properties. For instance, the researchers found that a deep sea sponge’s onion-like structure of silica layers provides a mechanism for preventing cracks. Nacre has a “brick-and-mortar” arrangement of minerals that generates a strong bond between the mineral layers, making the material extremely tough.

“In this context, there is a wide range of multiscale characterization and computational modeling techniques that are well established for studying the complexities of biological and biomimetic materials, which can be easily translated into the cement community,” says Masic.

Applying the information they learned from investigating biological materials, as well as knowledge they gathered on existing cement paste design tools, the team developed a general, bioinspired framework, or methodology, for engineers to design cement, “from the bottom up.”

The framework is essentially a set of guidelines that engineers can follow, in order to determine how certain additives or ingredients of interest will impact cement’s overall strength and durability. For instance, in a related line of research, Buyukozturk is looking into volcanic ash [emphasis mine] as a cement additive or substitute. To see whether volcanic ash would improve cement paste’s properties, engineers, following the group’s framework, would first use existing experimental techniques, such as nuclear magnetic resonance, scanning electron microscopy, and X-ray diffraction to characterize volcanic ash’s solid and pore configurations over time.

Researchers could then plug these measurements into models that simulate concrete’s long-term evolution, to identify mesoscale relationships between, say, the properties of volcanic ash and the material’s contribution to the strength and durability of an ash-containing concrete bridge. These simulations can then be validated with conventional compression and nanoindentation experiments, to test actual samples of volcanic ash-based concrete.

Ultimately, the researchers hope the framework will help engineers identify ingredients that are structured and evolve in a way, similar to biomaterials, that may improve concrete’s performance and longevity.

“Hopefully this will lead us to some sort of recipe for more sustainable concrete,” Buyukozturk says. “Typically, buildings and bridges are given a certain design life. Can we extend that design life maybe twice or three times? That’s what we aim for. Our framework puts it all on paper, in a very concrete way, for engineers to use.”

This is not the only team looking at new methods for producing the material, my Dec. 24, 2012 posting features a number of ‘concrete’ research projects.

Also, I highlighted the reference to ‘volcanic ash’ as it reminded me of Roman concrete which has lasted for over 2000 years and includes volcanic sand and volcanic rock.  You can read more about it in a Dec. 18, 2014 article by Mark Miller for Ancient Origins where he describes the wonders of the material and what was then a recent discovery of the Romans’ recipe.

I have two links and citations, first, the MIT paper, then the paper on Roman concrete.

Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach by Steven D. Palkovic, Dieter B. Brommer, Kunal Kupwade-Patil, Admir Masic, Markus J. Buehler, Oral Büyüköztürk.Construction and Building Materials Volume 115, 15 July 2016, Pages 13–31.  doi:10.1016/j.conbuildmat.2016.04.020

Mechanical resilience and cementitious processes in Imperial Roman architectural mortar by Marie D. Jackson, Eric N. Landis, Philip F. Brune, Massimo Vitti, Heng Chen, Qinfei Li, Martin Kunz, Hans-Rudolf Wenk, Paulo J. M. Monteiro, and Anthony R. Ingraffea. Proceedings of the National Academy of Sciences  vol. 111 no. 52 18484–18489, doi: 10.1073/pnas.1417456111

The first paper is behind a paywall but the second one appears to be open access.

Mimicking nature’s ‘anti-freeze’

Some frogs can survive being frozen for weeks and that’s the property scientists at the University of Leeds (UK) are trying to mimic according to a May 19, 2016 news item on Nanowerk (Note: A link has been removed),

The new research, published today [May 18, 2016] in the print edition of the Journal of Physical Chemistry B (“Low-Density Water Structure Observed in a Nanosegregated Cryoprotectant Solution at Low Temperatures from 285 to 238 K”), reveals how glycerol prevents ice crystals from forming in water as the solution is cooled to -35°C, with important implications for improving cryoprotectants used in fertility treatments and food storage.

A May 19, 2016 University of Leeds press release (also on EurekAlert), which originated the news item, provides more detail (Note: A link has been removed),

Dr Lorna Dougan from the University’s School of Physics and Astronomy, who leads the research group, said: “The experiments provide more insight into the fundamental properties of water. It raises questions about what cryoprotectants are doing in living organisms and could help us take steps to understanding how these organisms survive.

“If we understand what glycerol is doing we might be able to fine-tune some of these cryoprotectants that are used to find more effective combinations.”

Cryoprotectant molecules, including glycerol, play an important role in protecting cells and tissues from harmful ice crystals when they are cooled to sub-zero temperatures during freeze storage. Experts have adopted the use of cryoprotectants in fertility treatments and food storage, but not as effectively as in nature.

It is the ability of organisms that can survive in extreme cold environments – known as ‘psychrophiles’ – that inspired the team of physicists to unpick the biological rules that allow their survival.

In winter months, for example, the Eastern Wood frog in North America survives being frozen to temperatures as low as -8°C for weeks, and then in spring thaws out and continues to live perfectly healthily.

To understand how reptiles like the Eastern Wood frog can freeze and thaw, the team used a Science and Technology Facilities Council (STFC) instrument called SANDALS that was purpose-built for investigating the structure of liquids and amorphous materials.

They wanted to answer the fundamental question of how cryoprotectants alter the structure of water at low temperatures, as it is the water structure that is so important in leading to potential ice damage.

The SANDALS instrument allowed the team to see, at the molecular level, that the water and glycerol segregated into clusters. When they looked in more detail, they found the water looked similar to a low density form of itself, showing all the signs it was about to freeze but then it did not. Instead, the glycerol molecules encapsulated the water, preventing the formation of an icy network.

The team will now use these results as a platform for discovering the next generation of cryoprotectants.

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

Low-Density Water Structure Observed in a Nanosegregated Cryoprotectant Solution at Low Temperatures from 285 to 238 K by J. J. Towey, A. K. Soper, and L. Dougan. J. Phys. Chem. B, 2016, 120 (19), pp 4439–4448 DOI: 10.1021/acs.jpcb.6b01185 Publication Date (Web): March 18, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

I did search for images of Eastern Wood Frogs but they have to be paid for. These frogs must be a very much in demand as I’ve haven’t encountered this before. You can usually find what you want on Wikipedia or on a frog enthusiast site. It’s not an Eastern one but here’s a Wood Frog (from Wikipedia),

Lithobates sylvaticus (Woodfrog) Date: 3 July 2011, 19:31 Author:Brian Gratwicke This file is licensed under the Creative Commons Attribution 2.0 Generic license.

Lithobates sylvaticus (Woodfrog)
Date: 3 July 2011, 19:31
Author: Brian Gratwicke
This file is licensed under the Creative Commons Attribution 2.0 Generic license.

A Victoria & Albert Museum installation integrates of biomimicry, robotic fabrication and new materials research in architecture

The Victoria & Albert Museum (V&A) in London, UK, opened its Engineering Season show on May 18, 2016 (it runs until Nov. 6, 2016) featuring a robot installation and an exhibition putting the spotlight on Ove Arup, “the most significant engineer of the 20th century” according to the V&A’s May ??, 2016 press release,

The first major retrospective of the most influential engineer of the 20th century and a site specific installation inspired by nature and fabricated by robots will be the highlights of the V&A’s first ever Engineering Season, complemented by displays, events and digital initiatives dedicated to global engineering design. The V&A Engineering Season will highlight the importance of engineering in our daily lives and consider engineers as the ‘unsung heroes’ of design, who play a vital and creative role in the creation of our built environment.

Before launching into the robot/biomimicry part of this story, here’s a very brief description of why Ove Arup is considered so significant and influential,

Engineering the World: Ove Arup and the Philosophy of Total Design will explore the work and legacy of Ove Arup (1895-1988), … . Ove pioneered a multidisciplinary approach to design that has defined the way engineering is understood and practiced today. Spanning 100 years of engineering and architectural design, the exhibition will be guided by Ove’s writings about design and include his early projects, such as the Penguin Pool at London Zoo, as well as renowned projects by the firm including Sydney Opera House [Australia] and the Centre Pompidou in Paris. Arup’s collaborations with major architects of the 20th century pioneered new approaches to design and construction that remain influential today, with the firm’s legacy visible in many buildings across London and around the world. It will also showcase recent work by Arup, from major infrastructure projects like Crossrail and novel technologies for acoustics and crowd flow analysis, to engineering solutions for open source housing design.

Robots, biomimicry and the Elytra Filament Pavilion

A May 18, 2016 article by Tim Master for BBC (British Broadcasting Corporation) news online describes the pavilion installation,

A robot has taken up residence at the Victoria & Albert Musuem to construct a new installation at its London gardens.

The robot – which resembles something from a car assembly line – will build new sections of the Elytra Filament Pavilion over the coming months.

The futuristic structure will grow and change shape using data based on how visitors interact with it.

Elytra’s canopy is made up of 40 hexagonal cells – made from strips of carbon and glass fibre – which have been tightly wound into shape by the computer-controlled Kuka robot.

Each cell takes about three hours to build. On certain days, visitors to the V&A will be able to watch the robot create new cells that will be added to the canopy.

Here are some images made available by V&A,

Elytra Filament Pavilion arriving at the V&A, 2016. © Victoria and Albert Museum, London

Elytra Filament Pavilion arriving at the V&A, 2016. © Victoria and Albert Museum, London

Kuka robot weaving Elytra Filament Pavilion cell fibres, 2016. © Victoria and Albert Museum, London

Kuka robot weaving Elytra Filament Pavilion cell fibres, 2016. © Victoria and Albert Museum, London

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Elytra Filament Pavilion at the V&A, 2016. © Victoria and Albert Museum, London

Elytra Filament Pavilion at the V&A, 2016. © Victoria and Albert Museum, London

Here’s more detail from the V&A’s Elytra Filament Pavilion installation description,

Elytra Filament Pavilion has been created by experimental German architect Achim Menges with Moritz Dörstelmann, structural engineer Jan Knippers and climate engineer Thomas Auer.

Menges and Knippers are leaders of research institutes at the University of Stuttgart that are pioneering the integration of biomimicry, robotic fabrication and new materials research in architecture. This installation emerges from their ongoing research projects and is their first-ever major commission in the UK.

The pavilion explores the impact of emerging robotic technologies on architectural design, engineering and making.

Its design is inspired by lightweight construction principles found in nature, the filament structures of the forewing shells of flying beetles known as elytra. Made of glass and carbon fibre, each component of the undulating canopy is produced using an innovative robotic winding technique developed by the designers. Like beetle elytra, the pavilion’s filament structure is both very strong and very light – spanning over 200m2 it weighs less than 2,5 tonnes.

Elytra is a responsive shelter that will grow over the course of the V&A Engineering Season. Sensors in the canopy fibres will collect data on how visitors inhabit the pavilion and monitor the structure’s behaviour, ultimately informing how and where the canopy grows. During a series of special events as part of the Engineering Season, visitors will have the opportunity to witness the pavilion’s construction live, as new components are fabricated on-site by a Kuka robot.

Unfortunately, I haven’t been able to find more technical detail, particularly about the materials being used in the construction of the pavilion, on the V&A website.

One observation, I’m a little uncomfortable with how they’re gathering data “Sensors in the canopy fibres will collect data on how visitors inhabit the pavilion … .” It sounds like surveillance to me.

Nonetheless, the Engineering Season offers the promise of a very intriguing approach to fulfilling the V&A’s mandate as a museum dedicated to decorative arts and design.

Spider webs inspire liquid wire

Courtesy University of Oxford

Courtesy University of Oxford

Usually, when science talk runs to spider webs the focus is on strength but this research from the UK and France is all about resilience. From a May 16, 2016 news item on phys.org,

Why doesn’t a spider’s web sag in the wind or catapult flies back out like a trampoline? The answer, according to new research by an international team of scientists, lies in the physics behind a ‘hybrid’ material produced by spiders for their webs.

Pulling on a sticky thread in a garden spider’s orb web and letting it snap back reveals that the thread never sags but always stays taut—even when stretched to many times its original length. This is because any loose thread is immediately spooled inside the tiny droplets of watery glue that coat and surround the core gossamer fibres of the web’s capture spiral.

This phenomenon is described in the journal PNAS by scientists from the University of Oxford, UK and the Université Pierre et Marie Curie, Paris, France.

The researchers studied the details of this ‘liquid wire’ technique in spiders’ webs and used it to create composite fibres in the laboratory which, just like the spider’s capture silk, extend like a solid and compress like a liquid. These novel insights may lead to new bio-inspired technology.

A May 16, 2016 University of Oxford press release (also on EurekAlert), which originated the news item, provides more detail,

Professor Fritz Vollrath of the Oxford Silk Group in the Department of Zoology at Oxford University said: ‘The thousands of tiny droplets of glue that cover the capture spiral of the spider’s orb web do much more than make the silk sticky and catch the fly. Surprisingly, each drop packs enough punch in its watery skins to reel in loose bits of thread. And this winching behaviour is used to excellent effect to keep the threads tight at all times, as we can all observe and test in the webs in our gardens.’

The novel properties observed and analysed by the scientists rely on a subtle balance between fibre elasticity and droplet surface tension. Importantly, the team was also able to recreate this technique in the laboratory using oil droplets on a plastic filament. And this artificial system behaved just like the spider’s natural winch silk, with spools of filament reeling and unreeling inside the oil droplets as the thread extended and contracted.

Dr Hervé Elettro, the first author and a doctoral researcher at Institut Jean Le Rond D’Alembert, Université Pierre et Marie Curie, Paris, said: ‘Spider silk has been known to be an extraordinary material for around 40 years, but it continues to amaze us. While the web is simply a high-tech trap from the spider’s point of view, its properties have a huge amount to offer the worlds of materials, engineering and medicine.

‘Our bio-inspired hybrid threads could be manufactured from virtually any components. These new insights could lead to a wide range of applications, such as microfabrication of complex structures, reversible micro-motors, or self-tensioned stretchable systems.’

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

In-drop capillary spooling of spider capture thread inspires hybrid fibers with mixed solid–liquid mechanical properties by Hervé Elettro, Sébastien Neukirch, Fritz Vollrath, and Arnaud Antkowiak. PNAS doi: 10.1073/pnas.1602451113

This paper appears to be open access.

Mimicking the sea urchin’s mouth and teeth for space exploration

Researchers at the University of California at San Diego (UCSD) have designed a new device for use in space exploration that is based on the structure and mechanics of a sea urchin’s mouth and teeth. From a May 2, 2016 news item on ScienceDaily,

The sea urchin’s intricate mouth and teeth are the model for a claw-like device developed by a team of engineers and marine biologists at the University of California, San Diego to sample sediments on other planets, such as Mars. The researchers detail their work in a recent issue of the Journal of Visualized Experiments.

A May 2, 2016 UCSD press release (also on EurekAlert), which originated the news item, expands on the theme by hearkening back to Aristotle (a Greek philosopher),

The urchin’s mouthpiece was first described in detail by the Greek philosopher Aristotle, earning it the nickname “Aristotle’s lantern.” It is comprised of an intricate framework of muscles and five curved teeth with triangle-shaped tips that can scrape, cut, chew and bore holes into the toughest rocks—a colony of sea urchins can destroy an entire kelp forest by churning through rock and uprooting seaweed.  The teeth are arranged in a dome-like formation that opens outwards and closes inwards in a smooth motion, similar to a claw in an arcade prize-grabbing machine.

The news release goes on to describe the methodology,

Bio-inspiration for the study came from pink sea urchins (Strongylocentrotus fragilis), which live off the West Coast of North America, at depths ranging from 100 to 1000 meters in the Pacific Ocean. The urchins were collected for scientific research by the Scripps Institution of Oceanography at UC San Diego.

Researchers extracted the urchins’ mouthpieces, scanned them with microCT, essentially a 3D microscopy technique, and analyzed the structures at the National Center for Microscopy and Imaging Research at the School of Medicine at UC San Diego. This allowed engineers to build a highly accurate model of the mouthpiece’s geometry.

Researchers also used finite element analysis to investigate the structure of the teeth, a method that allowed them to determine the importance of the keel to the teeth’s performance.

Engineers then turned the microCT data into a user-friendly file that a team of undergraduate engineering students at UC San Diego used to start iterating prototypes of the claw-like device, under the supervision of Ph.D. students in McKittrick’s lab.

The first iteration was very close to the mouthpiece’s natural structure, but didn’t do a very good job at grasping sand.  In the second iteration, students flattened the pointed end of the teeth so the device would scoop up sand better. But the device wasn’t opening quite right. Finally, on the third iteration, they connected the teeth differently to the rest of the device, which allowed it to open much easier. The students were able to quickly modify each prototype by using 3D printers in the UC San Diego Design Studio.

The device was then attached to a remote-controlled small rover. The researchers first tested the claw on beach sand, where it performed well. They then used the claw on sand that simulates Martian soil in density and humidity (or lack thereof). The device was able to scoop up sand efficiently. Researchers envision a fleet of mini rovers equipped with the claw that could be deployed to collect samples and bring them back to a main rover. Frank hopes that this design will be of interest to NASA [US National Aeronautics and Space Administraton] and SpaceX [a private enterprise for designing, manufacturing, and launching craft bound for space].

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

A Protocol for Bioinspired Design: A Ground Sampler Based on Sea Urchin Jaws by Michael B. Frank, Steven E. Naleway, Taylor S. Wirth, Jae-Young Jung, Charlene L. Cheung, Faviola B. Loera, Sandra Medina, Kirk N. Sato, Jennifer R. A. Taylor, Joanna McKittrick. Journal of Visualized Experiments, 2016; (110) DOI: 10.3791/53554 Date Published: 4/24/2016

This paper and its video are behind a paywall. For those unfamiliar with the Journal of Visualized Experiments (JOVE), it is focused largely on videos which demonstrate the various techniques and protocols being described in the accompanying papers.

The researchers have made an introductory video available courtesy of UCSD,

Chinese scientists develop a novel 3D fabrication technique for bio-inspired hierarchical structures

An April 14, 2016 news item on phys.org describes a new 3D fabrication technique devised by Chinese scientists,

Nature is no doubt the world’s best biological engineer, whose simple, exquisite but powerful designs have inspired scientists and engineers to tackle the challenges of technologies for centuries. Scientists recently mimicked the surface structure of a moth’s eye, a unique structure with an antireflective property, to develop a highly light-absorbent graphene material. This is breakthrough [sic] in solar cell technology. Rice leaves and butterfly wings also have unique self-cleaning surface characteristics, which inspire scientists to develop novel materials resistant to biofouling. The bio-inspired periodic multi-scale structures, called hierarchical structures, have recently caught broad attention among scientists in various applications such as solar cells, Light-emitting diodes (LEDs), biomaterials and anti-bacterial surfaces.

An April 14, 2016 Optical Society of American news release (also on EurekAlert), which originated the news item, provides more detail,

Although a number of techniques for fabricating bio-inspired hierarchical structures already exist, most conventional methods either involve complicated processes or are highly time-consuming and low cost-efficiency for industrial applications. Now, a team of researchers from Changchun University of Science and Technology, China, have developed a novel method for the rapid and maskless fabrication of bio-inspired hierarchical structures, using a technique called laser interference lithography.

Specifically, the researchers use the interference pattern of three-and four-beam lasers to fabricate ordered multi-scale surface structures on silicon substrates, with the pattern of hierarchical structures controllable by adjusting the parameters of incident light. In accordance with the theoretical and computer analysis, the researchers have experimentally demonstrated the novel technique’s potential in large-area, low-cost and high-volume 3D fabrication of micro and nanostructures. …

“We presented a flexible and direct method for fabricating ordered multi-scale 3D structures using three- and four-beam interference lithography,” said Zuobin Wang, the primary author and a professor of International Research Centre for Nano Handling and Manufacturing of China at the Changchun University of Science and Technology, China. “Compared with other patterning technologies, our method is simple and efficient in terms of obtaining bio-inspired hierarchical structures.”

Wang mentioned that for certain complicated surface structures, conventional techniques such as electron beam lithography may take several hours or a day to fabricate the pattern, while the laser interference approach only takes several minutes to generate the structure, which makes the technique suitable for high-volume industrial production.

“Laser interference lithography is a maskless patterning technique that uses the interference patterns generated from two or several coherent laser beams to fabricate micro and nanometer periodic patterns over large areas,” Wang said. Different from conventional patterning techniques like electron beam lithography, the laser interference technique enables fabricating the entire substrate surface with one single exposure or one-step lithography.

For example, in Wang’s experiment, the one-dimension multi-scale structure, that is, one-dimension oriented arrangement with the sinusoidal grooves covered with periodic line-like structures was fabricated by exposing the silicon substrate to three or four interfered beams for one time. The resultant surface pattern, though arranged in one direction, has three-dimension spatial structure. To obtain more complicated structures such as two-dimension oriented multi-scale structures, the researchers simply rotated the substrate by 90 degrees in the plane and applied second laser exposure to the surface.

“Laser interference lithography is capable of fabricating homogeneous micro and nanometer structured patterns over areas more than one square meter, which is either impossible or highly time or cost consuming for conventional techniques,” Wang said. These features make laser interference lithography superior to other techniques in terms of efficiency and high-volume production.

According to Wang, their experimental process is simple: a high power laser beam was split into three or four equal beams, which then were directed by mirrors to generate interference patterns to fabricate the surface structures. The laser parameters such as incident angle and azimuthal angle of each beam were adjusted by beam splitters and mirror positions. Other optical devices such as quarter-wave plates and polarizers were used to select the polarization mode and control the energy of laser beams.

“The laser beam parameters are selected according to the desired surface structure and corresponding interference energy distribution calculated from theoretical simulation. In other words, the shapes or patterns of hierarchical structures in our method are controllable by adjusting the parameters of each incident beams,” Wang noted.

According to Wang, the proposed technique could be used to fabricate optical or medical devices such as solar cells, antireflective coatings, self-cleaning and antibacterial surfaces and long-life artificial hip joints.

The researchers’ next step is to develop functional surface structures with controllable wettability, adhesion and reflectivity properties for optical, medical and mechanical applications.

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

Bio-inspired hierarchical patterning of silicon by laser interference lithography by Yaowei Hu, Zuobin Wang, Zhankun Weng, Miao Yu, and Dapeng Wang. Applied Optics Vol. 55, Issue 12, pp. 3226-3232 (2016) doi: 10.1364/AO.55.003226

I believe this paper is behind a paywall.

The researchers have provided this image as an illustration of their concept,

 Caption: This is a Scanning Electron Microscope (SEM) image of a moth eye. Credit: Zuobin Wang/Changchun University of Science and Technology, China


Caption: This is a Scanning Electron Microscope (SEM) image of a moth eye. Credit: Zuobin Wang/Changchun University of Science and Technology, China