Category Archives: biomimcry

How geckos self-clean, even in dusty environments

An Australian research team claims a world first with regard to ‘gecko research’ according to a March 16, 2014 news item on ScienceDaily,

In a world first, a research team including James Cook University [JCU] scientists has discovered how geckos manage to stay clean, even in dusty deserts.

The process, described in Interface, a journal of the Royal Society, may also turn out to have important human applications.

JCU’s Professor Lin Schwarzkopf said the group found that tiny droplets of water on geckos, for instance from condensing dew, come into contact with hundreds of thousands of extremely small hair-like spines that cover the animals’ bodies.

A March 16, 2015 JCU press release (also on EurekAlert), which originated the news item, provides more detail,

“If you have seen how drops of water roll off a car after it is waxed, or off a couch that’s had protective spray used on it, you’ve seen the process happening,” she said. “The wax and spray make the surface very bumpy at micro and nano levels, and the water droplets remain as little balls, which roll easily and come off with gravity or even a slight wind.”

The geckos’ hair-like spines trap pockets of air and work on the same principle, but have an even more dramatic effect. Through a scanning electron microscope, tiny water droplets can be seen rolling into each other and jumping like popcorn off the skin of the animal as they merge and release energy.

Scientists were aware that hydrophobic surfaces repelled water, and that the rolling droplets helped clean the surfaces of leaves and insects, but this is the first time it has been documented in a vertebrate animal. Box-patterned geckos live in semi-arid habitats, with little rain but may have dew forming on them when the temperature drops overnight.

Professor Schwarzkopf said the process may help geckos keep clean, as the water can carry small particles of dust and dirt away from their body. “They tend to live in dry environments where they can’t depend on it raining, and this keeps process them clean,” she said.

She said there were possible applications for marine-based electronics that have to shed water quickly in use and for possible “superhydrophobic” clothing that would not get wet or dirty and would never need washing.

I’ve been reading about self-cleaning products for years now. (sigh) Where are they? Despite this momentary lapse into sighing and wailing, I am much encouraged that scientists are still trying to figure out how to create self-cleaning products.

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

Removal mechanisms of dew via self-propulsion off the gecko skin by Gregory S. Watson, Lin Schwarzkopf, Bronwen W. Cribb, Sverre Myhra, Marty Gellender, and Jolanta A. Watson.
Interface, April 2015, Volume: 12 Issue: 105 DOI: 10.1098/rsif.2014.1396 Published 11 March 2015

This paper is open access.

Chameleon-like artificial skin

A March 12, 2015 news item on phys.org describes artificial skin inspired by chameleons,

Borrowing a trick from nature, engineers from the University of California at Berkeley have created an incredibly thin, chameleon-like material that can be made to change color—on demand—by simply applying a minute amount of force.

This new material-of-many-colors offers intriguing possibilities for an entirely new class of display technologies, color-shifting camouflage, and sensors that can detect otherwise imperceptible defects in buildings, bridges, and aircraft.

“This is the first time anybody has made a flexible chameleon-like skin that can change color simply by flexing it,” said Connie J. Chang-Hasnain, a member of the Berkeley team and co-author on a paper published today in Optica, The Optical Society’s (OSA) new journal.

A March 12, 2015 OSA news release (also on EurekAlert), which originated the news item, provides more information about this structural color project,

The colors we typically see in paints, fabrics, and other natural substances occur when white, broad spectrum light strikes their surfaces. The unique chemical composition of each surface then absorbs various bands, or wavelengths of light. Those that aren’t absorbed are reflected back, with shorter wavelengths giving objects a blue hue and longer wavelengths appearing redder and the entire rainbow of possible combinations in between. Changing the color of a surface, such as the leaves on the trees in autumn, requires a change in chemical make-up.

Recently, engineers and scientists have been exploring another approach, one that would create designer colors without the use of chemical dyes and pigments. Rather than controlling the chemical composition of a material, it’s possible to control the surface features on the tiniest of scales so they interact and reflect particular wavelengths of light. This type of “structural color” is much less common in nature, but is used by some butterflies and beetles to create a particularly iridescent display of color.

Controlling light with structures rather than traditional optics is not new. In astronomy, for example, evenly spaced slits known as diffraction gratings are routinely used to direct light and spread it into its component colors. Efforts to control color with this technique, however, have proved impractical because the optical losses are simply too great.

The authors of the Optica paper applied a similar principle, though with a radically different design, to achieve the color control they were looking for. In place of slits cut into a film they instead etched rows of ridges onto a single, thin layer of silicon. Rather than spreading the light into a complete rainbow, however, these ridges — or bars — reflect a very specific wavelength of light. By “tuning” the spaces between the bars, it’s possible to select the specific color to be reflected. Unlike the slits in a diffraction grating, however, the silicon bars were extremely efficient and readily reflected the frequency of light they were tuned to.

Fascinatingly, the reflected colors can be selected (from the news release),

Since the spacing, or period, of the bars is the key to controlling the color they reflect, the researchers realized it would be possible to subtly shift the period — and therefore the color — by flexing or bending the material.

“If you have a surface with very precise structures, spaced so they can interact with a specific wavelength of light, you can change its properties and how it interacts with light by changing its dimensions,” said Chang-Hasnain.

Earlier efforts to develop a flexible, color shifting surface fell short on a number of fronts. Metallic surfaces, which are easy to etch, were inefficient, reflecting only a portion of the light they received. Other surfaces were too thick, limiting their applications, or too rigid, preventing them from being flexed with sufficient control.

The Berkeley researchers were able to overcome both these hurdles by forming their grating bars using a semiconductor layer of silicon approximately 120 nanometers thick. Its flexibility was imparted by embedding the silicon bars into a flexible layer of silicone. As the silicone was bent or flexed, the period of the grating spacings responded in kind.

The semiconductor material also allowed the team to create a skin that was incredibly thin, perfectly flat, and easy to manufacture with the desired surface properties. This produces materials that reflect precise and very pure colors and that are highly efficient, reflecting up to 83 percent of the incoming light.

Their initial design, subjected to a change in period of a mere 25 nanometers, created brilliant colors that could be shifted from green to yellow, orange, and red – across a 39-nanometer range of wavelengths. Future designs, the researchers believe, could cover a wider range of colors and reflect light with even greater efficiency.

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

Flexible photonic metastructures for tunable coloration by Li Zhu, Jonas Kapraun, James Ferrara, and Connie J. Chang-Hasnain. Optica, Vol. 2, Issue 3, pp. 255-258 (2015)

http://dx.doi.org/10.1364/OPTICA.2.000255

This paper is open access (for now at least).

Final note: I recently wrote about research into how real chameleons are able to effect colour changes in a March 16, 2015 post.

Chameleons (male panther chameleons in particular)—colour revelation

Caption: These are male panther chameleons (Furcifer pardalis) photographed in Madagascar. Credit: © Michel Milinkovitch

Caption: These are male panther chameleons (Furcifer pardalis) photographed in Madagascar.
Credit: © Michel Milinkovitch

Researchers at Switzerland’s University of Geneva/Université de Genève (UNIGE) have revealed the mechanisms (note the plural) by which chameleons change their colour. From a March 10, 2015 news item on phys.org,

Many chameleons have the remarkable ability to exhibit complex and rapid color changes during social interactions. A collaboration of scientists within the Sections of Biology and Physics of the Faculty of Science from the University of Geneva (UNIGE), Switzerland, unveils the mechanisms that regulate this phenomenon.

In a study published in Nature Communications [March 10, 2015], the team led by professors Michel Milinkovitch and Dirk van der Marel demonstrates that the changes take place via the active tuning of a lattice of nanocrystals present in a superficial layer of dermal cells called iridophores. The researchers also reveal the existence of a deeper population of iridophores with larger and less ordered crystals that reflect the infrared light. The organisation of iridophores into two superimposed layers constitutes an evolutionary novelty and it allows the chameleons to rapidly shift between efficient camouflage and spectacular display, while providing passive thermal protection.

Male chameleons are popular for their ability to change colorful adornments depending on their behaviour. If the mechanisms responsible for a transformation towards a darker skin are known, those that regulate the transition from a lively color to another vivid hue remained mysterious. Some species, such as the panther chameleon, are able to carry out such a change within one or two minutes to court a female or face a competing male.

A March 10, 2015 University of Geneva press release on EurekAlert (French language version is here on the university website), which originated the news item, explains the chameleon’s ability as being due to its ability to display structural colour,

Besides brown, red and yellow pigments, chameleons and other reptiles display so-called structural colors. «These colors are generated without pigments, via a physical phenomenon of optical interference. They result from interactions between certain wavelengths and nanoscopic structures, such as tiny crystals present in the skin of the reptiles», says Michel Milinkovitch, professor at the Department of Genetics and Evolution at UNIGE. These nanocrystals are arranged in layers that alternate with cytoplasm, within cells called iridophores. The structure thus formed allows a selective reflection of certain wavelengths, which contributes to the vivid colors of numerous reptiles.

To determine how the transition from one flashy color to another one is carried out in the panther chameleon, the researchers of two laboratories at UNIGE worked hand in hand, combining their expertise in both quantum physics and in evolutionary biology. «We discovered that the animal changes its colors via the active tuning of a lattice of nanocrystals. When the chameleon is calm, the latter are organised into a dense network and reflect the blue wavelengths. In contrast, when excited, it loosens its lattice of nanocrystals, which allows the reflection of other colors, such as yellows or reds», explain the physicist Jérémie Teyssier and the biologist Suzanne Saenko, co-first authors of the article. This constitutes a unique example of an auto-organised intracellular optical system controlled by the chameleon.

The press release goes on to note that the iridophores have another function,

The scientists also demonstrated the existence of a second deeper layer of iridophores. «These cells, which contain larger and less ordered crystals, reflect a substantial proportion of the infrared wavelengths», states Michel Milinkovitch. This forms an excellent protection against the thermal effects of high exposure to sun radiations in low-latitude regions.

The organisation of iridophores in two superimposed layers constitutes an evolutionary novelty: it allows the chameleons to rapidly shift between efficient camouflage and spectacular display, while providing passive thermal protection.

In their future research, the scientists will explore the mechanisms that explain the development of an ordered nanocrystals lattice within iridophores, as well as the molecular and cellular mechanisms that allow chameleons to control the geometry of this lattice.

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

Photonic crystals cause active colour change in chameleons by Jérémie Teyssier, Suzanne V. Saenko, Dirk van der Marel, & Michel C. Milinkovitch. Nature Communications 6, Article number: 6368 doi:10.1038/ncomms7368 Published 10 March 2015

This article is open access.

Blue-striped limpets and their nanophotonic features

This is a structural colour story limpets and the Massachusetts Institute of Technology (MIT) and Harvard University. For the impatient here’s a video summary of the work courtesy of the researchers,

A Feb. 26, 2015 news item on ScienceDaily reiterates the details for those who like to read their science,

The blue-rayed limpet is a tiny mollusk that lives in kelp beds along the coasts of Norway, Iceland, the United Kingdom, Portugal, and the Canary Islands. These diminutive organisms — as small as a fingernail — might escape notice entirely, if not for a very conspicuous feature: bright blue dotted lines that run in parallel along the length of their translucent shells. Depending on the angle at which light hits, a limpet’s shell can flash brilliantly even in murky water.

Now scientists at MIT and Harvard University have identified two optical structures within the limpet’s shell that give its blue-striped appearance. The structures are configured to reflect blue light while absorbing all other wavelengths of incoming light. The researchers speculate that such patterning may have evolved to protect the limpet, as the blue lines resemble the color displays on the shells of more poisonous soft-bodied snails.

A Feb. 26, 2015 MIT news release (also on EurekAlert), which originated the news item, explains why this discovery is special,

The findings, reported this week in the journal Nature Communications, represent the first evidence of an organism using mineralized structural components to produce optical displays. While birds, butterflies, and beetles can display brilliant blues, among other colors, they do so with organic structures, such as feathers, scales, and plates. The limpet, by contrast, produces its blue stripes through an interplay of inorganic, mineral structures, arranged in such a way as to reflect only blue light.

The researchers say such natural optical structures may serve as a design guide for engineering color-selective, controllable, transparent displays that require no internal light source and could be incorporated into windows and glasses.

“Let’s imagine a window surface in a car where you obviously want to see the outside world as you’re driving, but where you also can overlay the real world with an augmented reality that could involve projecting a map and other useful information on the world that exists on the other side of the windshield,” says co-author Mathias Kolle, an assistant professor of mechanical engineering at MIT. “We believe that the limpet’s approach to displaying color patterns in a translucent shell could serve as a starting point for developing such displays.”

The news release then reveals how this research came about,

Kolle, whose research is focused on engineering bioinspired, optical materials — including color-changing, deformable fibers — started looking into the optical features of the limpet when his brother Stefan, a marine biologist now working at Harvard, brought Kolle a few of the organisms in a small container. Stefan Kolle was struck by the mollusk’s brilliant patterning, and recruited his brother, along with several others, to delve deeper into the limpet shell’s optical properties.

To do this, the team of researchers — which also included Ling Li and Christine Ortiz at MIT and James Weaver and Joanna Aizenberg at Harvard — performed a detailed structural and optical analysis of the limpet shells. They observed that the blue stripes first appear in juveniles, resembling dashed lines. The stripes grow more continuous as a limpet matures, and their shade varies from individual to individual, ranging from deep blue to turquoise.

The researchers scanned the surface of a limpet’s shell using scanning electron microscopy, and found no structural differences in areas with and without the stripes — an observation that led them to think that perhaps the stripes arose from features embedded deeper in the shell.

To get a picture of what lay beneath, the researchers used a combination of high-resolution 2-D and 3-D structural analysis to reveal the 3-D nanoarchitecture of the photonic structures embedded in the limpets’ translucent shells.

What they found was revealing: In the regions with blue stripes, the shells’ top and bottom layers were relatively uniform, with dense stacks of calcium carbonate platelets and thin organic layers, similar to the shell structure of other mollusks. However, about 30 microns beneath the shell surface the researchers noted a stark difference. In these regions, the researchers found that the regular plates of calcium carbonate morphed into two distinct structural features: a multilayered structure with regular spacing between calcium carbonate layers resembling a zigzag pattern, and beneath this, a layer of randomly dispersed, spherical particles.

The researchers measured the dimensions of the zigzagging plates, and found the spacing between them was much wider than the more uniform plates running through the shell’s unstriped sections. They then examined the potential optical roles of both the multilayer zigzagging structure and the spherical particles.

Kolle and his colleagues used optical microscopy, spectroscopy, and diffraction microscopy to quantify the blue stripe’s light-reflection properties. They then measured the zigzagging structures and their angle with respect to the shell surface, and determined that this structure is optimized to reflect blue and green light.

The researchers also determined that the disordered arrangement of spherical particles beneath the zigzag structures serves to absorb transmitted light that otherwise could de-saturate the reflected blue color.

From these results, Kolle and his team deduced that the zigzag pattern acts as a filter, reflecting only blue light. As the rest of the incoming light passes through the shell, the underlying particles absorb this light — an effect that makes a shell’s stripes appear even more brilliantly blue.

And, for those who can never get enough detail, the news release provides a bit more than the video,

The team then sought to tackle a follow-up question: What purpose do the blue stripes serve? The limpets live either concealed at the base of kelp plants, or further up in the fronds, where they are visually exposed. Those at the base grow a thicker shell with almost no stripes, while their blue-striped counterparts live higher on the plant.

Limpets generally don’t have well-developed eyes, so the researchers reasoned that the blue stripes must not serve as a communication tool, attracting one organism to another. Rather, they think that the limpet’s stripes may be a defensive mechanism: The mollusk sits largely exposed on a frond, so a plausible defense against predators may be to appear either invisible or unappetizing. The researchers determined that the latter is more likely the case, as the limpet’s blue stripes resemble the patterning of poisonous marine snails that also happen to inhabit similar kelp beds.

Kolle says the group’s work has revealed an interesting insight into the limpet’s optical properties, which may be exploited to engineer advanced transparent optical displays. The limpet, he points out, has evolved a microstructure in its shell to satisfy an optical purpose without overly compromising the shell’s mechanical integrity. Materials scientists and engineers could take inspiration from this natural balancing act.

“It’s all about multifunctional materials in nature: Every organism — no matter if it has a shell, or skin, or feathers — interacts in various ways with the environment, and the materials with which it interfaces to the outside world frequently have to fulfill multiple functions simultaneously,” Kolle says. “[Engineers] are more and more focusing on not only optimizing just one single property in a material or device, like a brighter screen or higher pixel density, but rather on satisfying several … design and performance criteria simultaneously. We can gain inspiration and insight from nature.”

Peter Vukusic, an associate professor of physics at the University of Exeter in the United Kingdom, says the researchers “have done an exquisite job” in uncovering the optical mechanism behind the limpet’s conspicuous appearance.

“By using multiple and complementary analysis techniques they have elucidated, in glorious detail, the many structural and physiological factors that have given rise to the optical signature of this highly evolved system,” says Vukusic, who was not involved in the study. “The animal’s complex morphology is highly interesting for photonics scientists and technologists interested in manipulating light and creating specialized appearances.”

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

A highly conspicuous mineralized composite photonic architecture in the translucent shell of the blue-rayed limpet by Ling Li, Stefan Kolle, James C. Weaver, Christine Ortiz, Joanna Aizenberg & Mathias Kolle. Nature Communications 6, Article number: 6322 doi:10.1038/ncomms7322 Published 26 February 2015

This article is open access.

Nanomaterials, the European Commission, and functionality

A Feb. 17, 2015 news item on Nanowerk features a special thematic issue of Science for Environment Policy, a free news and information service published by the European
Commission’s Directorate-General Environment, which provides the latest environmental policy-relevant research findings (Note: A link has been removed),

Nanomaterials – at a scale of one thousand times smaller than a millimetre – offer the promise of radical technological development. Many of these will improve our quality of life, and develop our economies, but all will be measured against the overarching principle that we do not make some error, and harm ourselves and our environment by exposure to new forms of hazard. This Thematic Issue (“Nanomaterials’ functionality”; free pdf download) explores recent developments in nanomaterials research, and possibilities for safe, practical and resource-efficient applications.

You can find Nanomaterials’ functionality thematic issue here; the issue includes.

Several articles in this Thematic Issue illustrate how nanotechnology is likely to further revolutionise that arena, for example in capturing sunlight and turning it into usable electrical energy. The article ‘Solar cell efficiency boosted with pine tree-like nanotube needle’, describes how light collected from the sun can be bounced around many times inside a nanostructure to improve the chance of it exciting electrons, and ‘Nanotechnology cuts costs and improves efficiency of photovoltaic cells’ shows how electrons that are released can be captured by the large surface area of ‘nano-tree like’ anodes. Together these ensure that more of the sunlight is transformed to captured electrons and electrical power. The article ‘New energy-efficient manufacture of perovskite solar cells’ goes further, and suggests that the existing titanium dioxide that is currently used in solar cells could be replaced by perovskites, yielding quite dramatic improvements in energy conversion, at low device fabrication costs. …

The article ‘New quantum dot process could lead to super-efficient light-producing technology’ describes how anisotropic (elongated, non-spherical) indium-gallenium nitride quantum dots, or proximity to an anisotropic surface, can lead quantum dots to emit polarised light, potentially enabling 3D television screens, optical computers and other applications, at much lower cost. ‘The potential of new building block-like nanomaterials: van der Waals heterostructures’ and ‘Graphene’s health effects summarised in new guide’ touch on the possibility of engineering ‘building block-crystals’ by arranging different 2D nanostructures such as graphene into low dimension crystals, which allows us, for example, to lower the loss of energy in transmitting electricity. There are also quite novel directions underpinning ‘green nanochemistry’ — illustrated by the potential of silk-based electron-beam resists (in the article ‘Making nano-scale manufacturing eco-friendly with silk’) — to be eco-friendly, and have new functionalities.

… [p. 3 PDF]

In addition to highlighting various research areas by mentioning articles included the issue, the editorial makes its case for commercializing nanomaterials and for the European establishment’s precautionary approach to doing so,

European institutions and organisations have been at the forefront of efforts to ensure safe and practical implementation of nanotechnology. Significant efforts have been made to address knowledge gaps through research, the financing of responsible innovation, and the upgrading of the regulatory framework to render it capable of addressing the new challenges. There are solid reasons for institutional attention to the issues. Succinctly put, the passing around and modification of natural nanoparticles and macromolecules (for example, proteins) within our bodies is the foundation of much of life. In doing so we regulate and send signals between cells and organs. It is therefore appropriate that questions should be asked about engineered nanoparticles and how they interact with us, and whether they could lead to unforeseen hazards. Those are substantive issues, and answering them well will support the creative drive towards real innovation for many decades to come, and honour our commitments to future generations. [p. 4 PDF]

This special issue provide links for more information and citations for the research papers the articles are based on.

A bio-inspired robotic sock from Singapore’s National University

Should you ever be confined to a bed over a long period of time or find yourself unable to move your legs at will, this robotic sock could help you avoid blood clots according to a Feb. 10, 2015 National University of Singapore news release (also on EurekAlert but dated Feb. 13, 2015),

Patients who are bedridden or unable to move their legs are often at risk of developing Deep Vein Thrombosis (DVT), a potentially life-threatening condition caused by blood clots forming along the lower extremity veins of the legs. A team of researchers from the National University of Singapore’s (NUS) Yong Loo Lin School of Medicine and Faculty of Engineering has invented a novel sock that can help prevent DVT and improve survival rates of patients.

Equipped with soft actuators that mimic the tentacle movements of corals, the robotic sock emulates natural lower leg muscle contractions in the wearer’s leg, thereby promoting blood circulation throughout the wearer’s body. In addition, the novel device can potentially optimise therapy sessions and enable the patient’s lower leg movements to be monitored to improve therapy outcomes.

The invention is created by Assistant Professor Lim Jeong Hoon from the NUS Department of Medicine, as well as Assistant Professor Raye Yeow Chen Hua and first-year PhD candidate Mr Low Fanzhe of the NUS Department of Biomedical Engineering.

The news release goes on to contrast this new technique with the pharmacological and other methods currently in use,

Current approaches to prevent DVT include pharmacological methods which involve using anti-coagulation drugs to prevent blood from clotting, and mechanical methods that involve the use of compressive stimulations to assist blood flow.

While pharmacological methods are competent in preventing DVT, there is a primary detrimental side effect – there is higher risk of excessive bleeding which can lead to death, especially for patients who suffered hemorrhagic stroke. On the other hand, current mechanical methods such as the use of compression stockings have not demonstrated significant reduction in DVT risk.

In the course of exploring an effective solution that can prevent DVT, Asst Prof Lim, who is a rehabilitation clinician, was inspired by the natural role of the human ankle muscles in facilitating venous blood flow back to the heart. He worked with Asst Prof Yeow and Mr Low to derive a method that can perform this function for patients who are bedridden or unable to move their legs.

The team turned to nature for inspiration to develop a device that is akin to human ankle movements. They found similarities in the elegant structural design of the coral tentacle, which can extend to grab food and contract to bring the food closer for consumption, and invented soft actuators that mimic this “push and pull” mechanism.

By integrating the actuators with a sock and the use of a programmable pneumatic pump-valve control system, the invention is able to create the desired robot-assisted ankle joint motions to facilitate blood flow in the leg.

Explaining the choice of materials, Mr Low said, “We chose to use only soft components and actuators to increase patient comfort during use, hence minimising the risk of injury from excessive mechanical forces. Compression stockings are currently used in the hospital wards, so it makes sense to use a similar sock-based approach to provide comfort and minimise bulk on the ankle and foot.”

The sock complements conventional ankle therapy exercises that therapists perform on patients, thereby optimising therapy time and productivity. In addition, the sock can be worn for prolonged durations to provide robot-assisted therapy, on top of the therapist-assisted sessions. The sock is also embedded with sensors to track the ankle joint angle, allowing the patient’s ankle motion to be monitored for better treatment.

Said Asst Prof Yeow, “Given its compact size, modular design and ease of use, the soft robotic sock can be adopted in hospital wards and rehabilitation centres for on-bed applications to prevent DVT among stroke patients or even at home for bedridden patients. By reducing the risk of DVT using this device, we hope to improve survival rates of these patients.”

The team does not seem to have published any papers about this work although there are plans for clinical trials and commercialization (from the news release),

To further investigate the effectiveness of the robotic sock, Asst Prof Lim, Asst Prof Yeow and Mr Low will be conducting pilot clinical trials with about 30 patients at the National University Hospital over six months, starting March 2015. They hope that the pilot clinical trials will help them to obtain patient and clinical feedback to further improve the design and capabilities of the device.

The team intends to conduct trials across different local hospitals for better evaluation, and they also hope to commercialise the device in future.

The researchers have provided an image of the sock on a ‘patient’,

 Caption: NUS researchers (from right to left) Assistant Professor Raye Yeow, Mr Low Fanzhe and Dr Liu Yuchun demonstrating the novel bio-inspired robotic sock. Credit: National University of Singapore


Caption: NUS researchers (from right to left) Assistant Professor Raye Yeow, Mr Low Fanzhe and Dr Liu Yuchun demonstrating the novel bio-inspired robotic sock.
Credit: National University of Singapore

Fish that suck and why they matter

That headline is misleading, these fish (remoras) surprised scientists when research challenged longheld beliefs that they used suction to cling to various surfaces  From a Feb. 12, 2015 news item on ScienceDaily,

How does the hitchhiking, flat-headed remora fish attach to surfaces so securely yet release so easily? Suction was thought to be the easy answer, but Brooke Flammang, a biologist at the New Jersey Institute of Technology (NJIT), has proved this long-held conclusion to be only partly true.

Here’s an image of a remora clinging to a glass or plexiglass (?) wall,

Remoras stick to fast-moving sea creatures, but are also content to cling to aquarium tank walls. Courtesy: NJIT

Remoras stick to fast-moving sea creatures, but are also content to cling to aquarium tank walls. Courtesy: NJIT

A Feb. 12, 2015 NJIT press release (also on EurekAlert), which originated the news item, describes this research in the field of biomimicry,

Researchers have long studied animals like tree frogs, geckos, and spiders for their adhesive abilities, but what makes remoras unique in this group is they combine three key elements: the ability to securely fasten themselves for long periods of time; attach to different types of surfaces; release quickly without harming the surface.

Understanding the mechanics of this process could help researchers and engineers create or improve designs for any number of devices that need to stick well but then release quickly without harming the host, such as tags for tracking endangered species or bandages that really don’t hurt when you pull them off.

Using footage captured by GoPro cameras at SeaWorld’s Discovery Cove in Orlando, Flammang and NJIT researchers found that the adhesive disc on the remora’s head used to attach to sharks, rays and other pelagic hosts is actually a complex mechanism that includes a modified fin structure with teeny spikes (called lamellar spinules) that generate friction to adhere to the host. Remora head anatomy also differs from other fish in having unusually-structured blood vessels that may be the secret to how they maintain adhesion for hours at a time.

What intrigued Flammang, who studies the locomotion of fishes, integrating sensory biology, physiology, fluid dynamics, and bio-inspired robotics, is how remoras can alter the position and shape of the plates within the disc to change their position or quickly let go. She was able to observe the minute movements of remora disc components through the underwater footage provided by marine videographers.

“Remoras attach to other organisms for a variety of reasons: To find food, get protection, and find mates. Because the animals they attach to are powerful swimmers, they need a durable attachment that won’t be compromised by the host organism’s swimming, bending body. The adhesive disc the remora evolved from dorsal fin elements acts as a specialized suction cup that can bend and won’t slip,” Flammang said.

“We are applying the biomechanics of this mechanism to a robotic prototype that will be able to adhere to both rough and smooth surfaces through a variety of challenging conditions, both in water and air,” she said.

Flammang presented her research at the Society for Integrative and Comparative Biology’s annual conference in January.

“We have a lot to learn from the natural world. Being able to examine these animals up close can be very valuable to bioengineering. We are proud to support this important work,” added SeaWorld Parks & Entertainment’s Vice President of Research and Science, Dr. Judy St. Leger.

“In my lab at NJIT, we study the morphology of remoras, how they use muscular and vascular control to manipulate the disc for attachment on different surfaces, and the hydrodynamics of their approach, attachment, and release from a surface,” Flammang said. “Live remoras swim in our flow tank – a treadmill for fish – and we capture muscle activity recordings and high speed video of the fish swimming and attaching, as well as and the fluid moving around the fish and the attachment location.”

More broadly, she examines the way organisms interact with marine and aquatic environments and drive the evolutionary selection of morphology and function. She seeks to understand, for example, how different fish fins may give an advantage to certain species in a given habitat.

The two remoras (Echeneis naucrates) at SeaWorld’s Discovery Cove were valuable candidates for this study because they often attach themselves to a large acrylic panel that divides their dock-themed habitat from the park’s Grand Reef, a nearly 1million gallon tropical environment. Aquarists at Discovery Cove donned scuba gear to capture the underwater footage using a GoPro camera steadied with a suction cup arm to get the shots needed by the research team. Flammang and her colleagues then used mathematical algorithms to visualize motion that is not detected by the human eye.

There doesn’t seem to be a published paper for this work.

Studying the “feather-legged lace weaver’s” (Uloborus plumipes) web weaving abilities

It’s more commonly known in Britain as a ‘garden centre spider’ but I like ‘feather-legged lace weaver’ better. Before getting to the story, here’s an image of the spider in question,

The "garden center spider" (Uloborus plumipes) combs and pulls its silk and builds up an electrostatic charge to create sticky filaments just a few nanometers thick. It could inspire a new way to make super long and strong nanofibers. Credit: Hartmut Kronenberger & Katrin Kronenberger (Oxford University)

The “garden center spider” (Uloborus plumipes) combs and pulls its silk and builds up an electrostatic charge to create sticky filaments just a few nanometers thick. It could inspire a new way to make super long and strong nanofibers.
Credit: Hartmut Kronenberger & Katrin Kronenberger (Oxford University)

A Jan. 27, 2015 Oxford University press release (also on EurekAlert and in a Jan. 29, 2015 news item on Azonano) describes the research,

A spider commonly found in garden centres in Britain is giving fresh insights into how to spin incredibly long and strong fibres just a few nanometres thick.

The majority of spiders spin silk threads several micrometres thick but unusually the ‘garden centre spider’ or ‘feather-legged lace weaver’ [1] Uloborus plumipes can spin nano-scale filaments. Now an Oxford University team think they are closer to understanding how this is done. Their findings could lead to technologies that would enable the commercial spinning of nano-scale filaments.

The research was carried out by Katrin Kronenberger and Fritz Vollrath of Oxford University’s Department of Zoology and is reported in the journal Biology Letters.

Instead of using sticky blobs of glue on their threads to capture prey Uloborus uses a more ancient technique – dry capture threads made of thousands of nano-scale filaments that it is thought to electrically charge to create these fluffed-up catching ropes.

To discover the secrets of its nano-fibres the Oxford researchers collected adult female Uloborus lace weavers from garden centres in Hampshire, UK. They then took photographs and videos of the spiders’ spinning action and used three different microscopy techniques to examine the spiders’ silk-generating organs. Of particular interest was the cribellum, an ancient spinning organ not found in many spiders and consisting of one or two plates densely covered in tiny silk outlet nozzles (spigots).

Uloborus has unique cribellar glands, amongst the smallest silk glands of any spider, and it’s these that yield the ultra-fine ‘catching wool’ of its prey capture thread,’ said Dr Katrin Kronenberger of Oxford University’s Department of Zoology, the report’s first author. ‘The raw material, silk dope, is funnelled through exceptionally narrow and long ducts into tiny spinning nozzles or spigots. Importantly, the silk seems to form only just before it emerges at the uniquely-shaped spigots of this spider.’

False colour SEM image of a small part of the cribellum spinning plate with its unique silk outlets Image: Katrin Kronenberger (Oxford University) & David Johnston (University of Southampton)

False colour SEM image of a small part of the cribellum spinning plate with its unique silk outlets
Image: Katrin Kronenberger (Oxford University) & David Johnston (University of Southampton)

The cribellum of Uloborus is covered with thousands of tiny silk-producing units combining ducts that average 500 nanometres in length and spigots that narrow to a diameter of around 50 nanometres.

‘The swathe of gossamer, made of thousands of filaments, emerging from these spigots is actively combed out by the spider onto the capture thread’s core fibres using specialist hairs on its hind legs,’ said Professor Fritz Vollrath, the other author of the work. ‘This combing and hackling – violently pulling the thread – charges the fibres and the electrostatic interaction of this combination spinning process leads to regularly spaced, wool-like ‘puffs’ covering the capture threads. The extreme thinness of each filament, in addition to the charges applied during spinning, provides Van der Waals adhesion. And this makes these puffs immensely sticky.’

The cribellate capture thread of Uloborus plumipes, with its characteristic 'puffs', imaged with a Scanning Electron Microscope (SEM) Image: Fritz Vollrath (Oxford University)

The cribellate capture thread of Uloborus plumipes, with its characteristic ‘puffs’, imaged with a Scanning Electron Microscope (SEM)
Image: Fritz Vollrath (Oxford University)

Conventionally, synthetic polymers fibres are produced by hot-melt extrusion: these typically have diameters of 10 micrometres or above. But because thread diameter is integral to filament strength, technology that could enable the commercial production of nano-scale filaments would make it possible to manufacture stronger and longer fibres.

‘Studying this spider is giving us valuable insights into how it creates nano-scale filaments,’ said Professor Vollrath. ‘If we could reproduce its neat trick of electro-spinning nano-fibres we could pave the way for a highly versatile and efficient new kind of polymer processing technology.’

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

Spiders spinning electrically charged nano-fibres by Katrin Kronenberger and Fritz Vollrath. January 2015 Volume: 11 Issue: 1 DOI: 10.1098/rsbl.2014.0813 Published 28 January 2015

This is an open access paper. Note: Sometimes journals close access after a certain number of days so the paper may not be freely available after a certain time period.

‘Biomimicry’ patents

The US Patent and Trade Office (USPTO) has issued a new guidance document concerning ‘biomimicry’ patents according to David Bruggeman’s Dec. 20, 2014 post on his Pasco Phronesis blog (Note: Links have been removed),

The United States Patent and Trademark Office (USPTO) has released another guidance memo for patents derived ‘from nature’ (H/T ScienceInsider).  The USPTO released its first memo in March [2014], and between negative public comments and additional court action, releasing new guidance makes sense to me.

The USPTO is requesting comments on the guidance by March 16, 2014 and will be holding a holding a public forum for comments on Jan. 21, 2015. Here’s more detail about the comments from the USPTO 2014 Interim Guidance on Subject Matter Eligibility webpage,

The USPTO has prepared 2014 Interim Guidance on Patent Subject Matter Eligibility (Interim Eligibility Guidance) for USPTO personnel to use when determining subject matter eligibility under 35 U.S.C. 101 in view of recent decisions by the U.S. Supreme Court, including Alice Corp., Myriad, and Mayo.  The Interim Eligibility Guidance supplements the June 25, 2014 Preliminary Examination Instructions issued in view of Alice Corp. and supersedes the March 4, 2014 Procedure for Subject Matter Eligibility Analysis of Claims Reciting or Involving Laws of Nature/Natural Principles, Natural Phenomena, and/or Natural Products issued in view of Mayo and Myriad.  It is expected that the guidance will be updated in view of developments in the case law and in response to public feedback.

Any member of the public may submit written comments on the Interim Eligibility Guidance and claim example sets by electronic mail message over the Internet addressed to [email protected]  Electronic comments submitted in plain text are preferred, but also may be submitted in ADOBE® portable document format or MICROSOFT WORD® format.  The comments will be available for public inspection here at this Web page.  Because comments will be available for public inspection, information that is not desired to be made public, such as an address or a phone number, should not be included in the comments.  Comments will be accepted until March 16, 2015.

And there is also this about the public forum (from the Interim Guidance page),

A public forum will be hosted at the Alexandria campus of the USPTO on Jan. 21, 2015, to receive public feedback from any interested member of the public.  The Eligibility Forum will be an opportunity for the Office to provide an overview of the Interim Eligibility Guidance and for participants to present their interpretation of the impact of Supreme Court precedent on the complex legal and technical issues involved in subject matter eligibility analysis during examination by providing oral feedback on the Interim Eligibility Guidance and claim example sets.  Individuals will be provided an opportunity to make a presentation, to the extent that time permits.

Date and Location:  The Eligibility Forum will be held on Jan. 21, 2015, from 1pm – 5pm EST, in the Madison Auditorium North (Concourse Level), Madison Building, 600 Dulany Street, Alexandria, VA 22314. The meeting will also be accessible via WebEx.

Requests for Attendance at the Eligibility Forum:  Requests for attendance to the Eligibility Forum should be submitted by electronic mail through the Internet to [email protected] by JAN. 9, 2015.  Requests for attendance must include the attendee’s name, affiliation, title, mailing address, and telephone number.  An Internet e-mail address, if available, should also be provided.

If I understand David’s description of this guidance rightly, the use of something like curcumin (a constituent of turmeric) to heal wounds cannot be patented unless substantive changes have been made to the curcumin. In short, Laws Of Nature/Natural Principles, Natural Phenomena, And/Or Natural Products And/Or Abstract Ideas cannot be patented through the USPTO.

The science behind a firefly’s glow

A Dec. 17, 2014 news item on Nanotechnology Now describes research into the phenomenon of bioluminescence and fireflies,

 Fireflies used rapid light flashes to communicate. This “bioluminescence” is an intriguing phenomenon that has many potential applications, from drug testing and monitoring water contamination, and even lighting up streets using glow-in-dark trees and plants. Fireflies emit light when a compound called luciferin breaks down. We know that this reaction needs oxygen, but what we don’t know is how fireflies actually supply oxygen to their light-emitting cells. Using state-of-the-art imaging techniques, scientists from Switzerland and Taiwan have determined how fireflies control oxygen distribution to light up their cells. The work is published in Physical Review Letters.

A Dec. 17, 2014 EPFL (Ecole Polytechnique Fédérale de Lausanne) news release on EurekAlert provides more description of the work,

The firefly’s light-producing organ is called the “lantern”, and it is located in the insect’s abdomen. It looks like a series of tubes progressing into smaller ones and so one, like a tree’s branches growing into twigs. The function of these tubes, called, is to supply oxygen to the cells of the lantern, which contain luciferase and can produce light. However, the complexity of the firefly’s lantern has made it difficult to study this mechanism in depth, and reproduce it for technological applications.

Giorgio Margaritondo at EPFL, Yeukuang Hwu at the Academia Sinica and their colleagues at the National Tsing Hua University in Taiwan have successfully used two sophisticated imaging techniques to overcome the complexity of the firefly lantern and map out how oxygen is supplied to light-emitting cells. The techniques are called synchrotron phase contrast microtomography and transmission x-ray microscopy. They can scan down to the level of a single cell, even allowing researchers to look inside it.

By applying these techniques on live fireflies, the scientists were able to see the entire structure of the lantern for the first time, and to also make quantitative evaluations of oxygen distribution.

The imaging showed that the firefly diverts oxygen from other cellular functions and puts it into the reaction that breaks up luciferin. Specifically, the researchers found that oxygen consumption in the cell decreased, slowing down energy production. At the same time, oxygen supply switched to light-emission.

The study is the first to ever show the firefly’s lantern in such detail, while also providing clear evidence that it is optimized for light emission thanks to the state-of-the-art techniques used by the scientists. But Margaritondo points out another innovation: “The techniques we used have an advantage over, say, conventional x-ray techniques, which cannot easily distinguish between soft tissues. By using an approach based on changes in light intensity (phase-contrast) as opposed to light absorption (x-rays), we were able to achieve high-resolution imaging of the delicate firefly lantern.”

Here’s an image illustrating the work,

Tomographic Reconstruction of Part of the Firefly Lantern;  This detailed microimage shows larger channels branching into smaller ones, supplying oxygen for the firefly's light emission. The smallest channels are ten thousand times smaller than a millimeter and therefore invisible to other experimental probes: this has prevented scientists so far to unlock the mystery of firefly light flashes. Credit: Giorgio Margaritondo/EPFL

Tomographic Reconstruction of Part of the Firefly Lantern; This detailed microimage shows larger channels branching into smaller ones, supplying oxygen for the firefly’s light emission. The smallest channels are ten thousand times smaller than a millimeter and therefore invisible to other experimental probes: this has prevented scientists so far to unlock the mystery of firefly light flashes. Credit: Giorgio Margaritondo/EPFL

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

Firefly Light Flashing: Oxygen Supply Mechanism by Yueh-Lin Tsai, Chia-Wei Li, Tzay-Ming Hong, Jen-Zon Ho, En-Cheng Yang, Wen-Yen Wu, G. Margaritondo, Su-Ting Hsu, Edwin B. L. Ong, and Y. Hwu. Phys. Rev. Lett. 113, 258103 – Published 17 December 2014 DOI:  http://dx.doi.org/10.1103/PhysRevLett.113.258103

This paper is behind a paywall.