Tag Archives: gecko

Credit: Pauline Jennings.

Geckos can walk on water: here’s how (with a video)

A unique blend of surface tension and fast slapping is what allows the geckos to skid across water incredibly fast, at almost a meter a second. Inspired by geckos, scientists could one-day design rapid swimming robots designed for search and rescue in flooded areas.

Credit: Pauline Jennings.

Credit: Pauline Jennings.

Some insects, such as fishing spiders and water striders, habitually walk on the surface of water with ease. They do so thanks to their small surface area to volume ratio, which allows the water’s surface tension to support the animals. Geckos are far too large to be supported by the water’s surface tension, but these nifty creatures — which are also expert climbers, being able to cling to virtually any surface like Spiderman thanks to thousands of hairy structures that line the bottom of their feet — still manage the biblical feat.

[panel style=”panel-info” title=”What is surface tension” footer=””]Surface tension is the property of a liquid surface which acts as if it were a stretched elastic membrane. This phenomenon can be observed in the nearly spherical shape of small drops of liquids and of soap bubbles[/panel]

Researchers now think they know how. The team of biophysicists, which included Jasmine Nirody (University of Oxford) and Ardian Jusufi (Max Planck Institute), placed Asian house geckos (Hemidactylus platyurus) inside an experimental setup. The lab experiment consisted of a long water tank, with a plank attached across the top. The water’s surface tension was varied by adding soap.

One by one, the geckos were placed inside the tank while high-speed cameras recorded as the startled critters whizzed across the water. The footage showed that the geckos’ tiny legs slapped and stroked the water’s surface, which created air pockets that kept most of their bodies afloat. Remarkably, the geckos trotted across the surface of the water much as they do on land — their hydrophobic (water-repellant) skin and stabilizing tails also helped.

Gecko running over water in the wild. Credit: Pauline Jennings.

When soap was added — which causes water to lose its molecular adhesion — the geckos’ speed was reduced by half. This showed that surface tension plays a major role in the animals’ locomotion over the water’s surface. In fact, the geckos should have sunk if surface tension was the only thing keeping them afloat. It’s thanks to their rapid slapping that the geckos are still able to run over water — but only briefly because it requires a lot of energy, the authors reported in the journal Current Biology

“Animals move in such weird and different ways, and geckos are a good example of that,” says Nirody. “Geckos make use of several locomotive modes when running across water, which makes it more difficult to characterize.”

“Even knowing the extensive list of locomotive capabilities that geckos have in their arsenal, we were still very surprised at the speed at which they could dart across the water’s surface,” says Nirody. “The way that they combine several modalities to perform this feat is really remarkable.”

 

The gecko-gripper mounted a modified robotic arm at JPL, shown here lifting 45 lbs (20kg). Credit: JPL.

Gecko-inspired adhesive allows robots to grip wider range of objects

The agile gecko is one of nature’s best climbers — and its secret lies in the adhesive pads that line the feet. Now, researchers have combined the gecko toes’ adhesive properties with air-powered soft robotics to achieve unprecedented gripping sensitivity.

The gecko-gripper mounted a modified robotic arm at JPL, shown here lifting 45 lbs (20kg). Credit: JPL.

The gecko-gripper mounted a modified robotic arm at JPL, shown here lifting 45 lbs (20kg). Credit: JPL.

On a gecko’s toe, there are millions of microscopic hairs, each about 20 to 30 times smaller than a human hair. These hairs interact with molecules on the surface that the gecko is trying to grip at the atomic level, generating so-called van der Waals forces, which allow the toes to easily attach and detach when the gecko wills it.

Researchers at the University of California, San Diego, have devised an artificial version of the gecko toes’ microscopic features by employing synthetic materials and a technique called photolithography. In a three-step process, researchers first made a master mold of the millions of microscopic structures that line the gecko’s toes. Later, copies of the master mold were made using a low-cost, scalable method. A process called spin coating allowed the researchers to make as many copies of the adhesives sheets from the wax mold as they wished, at a rate of 10 to 20 sheets per hour. The soft robotic gripper itself was cast in 3D-print molds from a silicone-based rubber.

The team, which collaborated with NASA’s Jet Propulsion Laboratory, coated the 3D-printed fingers of a soft robotic gripper with the artificial gecko adhesive, which remarkably retained many of the same properties of its living, breathing counterpart.

During a series of experiments, the gecko-inspired adhesive allowed an air-powered robotic hand to grip a wide range of objects, from pipes to mugs. The adhesive was also strong and versatile enough to allow the robot to grasp objects at many different angles. The gripper also manipulated volcanic rocks whose porous and rough texture has always been challenging for gecko-like adhesives to cling to.

The gripper can also porous objects, like this volcanic rock. Credit: JPL.

The gripper can also porous objects, like this volcanic rock. Credit: JPL.

Because van der Waals forces are most effective on a larger surface area, the researchers had to develop control algorithms that allow the robot to distribute the right amount of force along the length of the finger. Thanks to optimal control and distribution of load, the gripper can lift various objects, in various positions, weighing up to 45 lbs (20kg).

“We realized that these two components, soft robotics and gecko adhesives, complement each other really well,” said Paul Glick, the paper’s first author and a Ph.D. student in the Bioinspired Robotics and Design Lab at the Jacobs School of Engineering at UC San Diego.

There are various applications that this research could enable. Since NASA was involved, one obvious area of interest is space exploration, where gecko-inspired adhesives might enable janitor-bots to collect trash or new grippers can attach to objects outside the International Space Station better and safer than ever before. Upcoming research will further investigate the adhesive’s potential for operation in zero-gravity.

Cyrtodactylus sp. Credit: Dr L. Lee Grismer.

Scientists discover 15 new gecko species in Myanmar

In the same small area on the island of Myanmar, scientists found and formally described 15 new colorful gecko species.

Cyrtodactylus sp. Credit: Dr L. Lee Grismer.

Cyrtodactylus sp. Credit: L. Lee Grismer.

The new species were discovered in the span of two weeks, along with other new species of other animals, such as snakes and frogs. All in all, the exploration, which was sponsored by the charity Fauna & Flora International, is responsible for describing 23 new species to science.

Lee Grismer of La Sierra University in California and colleagues were tasked with exploring a rather compact limestone habitat. These limestone blocks, which are just a few kilometers across, rise up some 400 meters above the rest of the surroundings. The elevation isolates the creatures living there from many types of predators, allowing new species to diverge from their lowland cousins. Hints abounded that there are many new species waiting to be discovered.

Cyrtodactylus sp. Credit: L. Lee Grismer

Cyrtodactylus sp. Credit: L. Lee Grismer

Indeed, the treasure trove of gecko species was rather easily discovered throughout the limestone blocks, which were heavily eroded and packed with caves of all sizes. Some of these caves are considered sacred, and are to this day guarded by monks. However, according to the researchers who explored the area, some of the limestone blocks are currently being mined, threatening this very delicate and isolated ecosystem.

“In an age of biodiversity crisis, managing and conserving these karst ecosystems throughout Southeast Asia should be given greater priority,” Grismer told Phys.org. 

“Hundreds of new species could face extinction without proper management,” he says, “but this [management] cannot happen unless these species are discovered and described – hence why we are ramping up our efforts in these regions.”

Credit: L Le Grismer.

Credit: L Le Grismer.

Most of the geckos (12) belong to a group called bent-toed geckos of the genus Cyrtodactylus, while the remaining three species are known as dwarf geckos from the genus Hemiphyllodactylus. The new species are described in two separate papers which are due to appear next week in the Journal of Natural History and the Zoological Journal of the Linnean Society. A third paper is still in preparation and describes another four bent-toed gecko species bringing the total number of new geckos to 19.

Hao Jiang, graduate student at Stanford shows a basketball being gripped by the gecko-inspired adhesive.

Gecko-inspired ‘Velcro’ could help cleanup our growing space junk problem

Hao Jiang, graduate student at Stanford shows a basketball being gripped by the gecko-inspired adhesive.

Hao Jiang, graduate student at Stanford shows a basketball being gripped by the gecko-inspired adhesive.

Stanford is experimenting with a new space-gripping technology that might rid the planet’s orbit of the millions and millions of debris collectively known as ‘space junk’. Though tiny, the debris travel at phenomenal relative velocities and any impact with a satellite or even a manned space station can spell disaster. The researchers were inspired by the gecko’s sticky pads to make sticky patches on a mechanical gripper which might one day be deployed on a ‘janitor’ spacecraft.

Cleanup on aisle five

Many of the things that work on Earth don’t work in space. You can’t, for instance, use suction or chemical adhesion (glue) to collect junk because of the vacuum. You can’t use magnets either because there’s a lot of space junk that’s made of glass or aluminum, though ESA is proposing using powerful magnetic beams to dislodge from orbit satellite fitted ‘magnetorquers’. The bottom line is that space physics is tricky, something which we all wish someone had told the nimrods who supervised the unconscionable dumping of all that junk into space.

In 1996, a French satellite was hit and damaged by the debris caused by some other French rocket which exploded a decade earlier. Yes, some people still think it’s actually a good idea to blow up stuff in the space. In 2007, for instance, China destroyed one of its old weather satellites with a missile causing 3,000 pieces of debris. Now, there are at least 170 million pieces of debris which range from 1cm to a few meters in diameter, all of which whizz past at more than 17,500 mph.

This scene from the movie Gravity is actually realistic.

This scene from the movie Gravity is actually realistic.

What makes space junk even more problematic is that there’s no viable solution in sight.  In 2012, Swiss scientists launched a pilot program called the CleanSpace One which is basically a ‘space janitor’. The function of the satellite is to track and offset debris so that their trajectory puts them on a collision course with Earth’s atmosphere. Japan has a mission called Kounotori 6 which can tether space junk with electromagnetic forces. Astroscale, a Japanese startup, plans is to launch a satellite called ELSA-1 that will track debris and stick to it with glue. Other ideas are even wilder, like using lasers to vaporize the surfaces of small pieces and force them down. But all of these have either failed or are in the making.

But maybe a ‘space gecko’ will pull it off after all.

“What we’ve developed is a gripper that uses gecko-inspired adhesives,” said Mark Cutkosky, professor of mechanical engineering and senior author of the paper. “It’s an outgrowth of work we started about 10 years ago on climbing robots that used adhesives inspired by how geckos stick to walls.”

Close up of the robotic gripper which is designed to grab objects in zero gravity using their gecko-inspired adhesive. Credit: Stanford.

Close up of the robotic gripper which is designed to grab objects in zero gravity using their gecko-inspired adhesive. Credit: Stanford.

A sticky problem

Stanford’s Cutkosky and colleagues think they can collect and eventually destroy space junk by gripping them with a robotic arm with a sticky touch. Gecko toes can stick to virtually any surface, not because of some glue of some sort, but rather thanks to Van der Waals forces — a. form of attraction which only works between the positive and negative charges of individual molecules that are within a few nanometers of one another.

At the center of the gecko’s Spider-Man-like clinging ability are its specialized pads, located on the reptile’s toes, comprised of various satae (bristle- or hair-like structures ) on the tip of which lie tiny structures called spatulae, each less than a micron wide. These allow attractive forces to arise between the adhesive setae and the surface.These forces are so strong that they not only allow for supporting the gecko’s weight but for even a highly robust human as well –  up to 133 kg can be sustained by the adherence forces between the gecko’s toes and a surface. This feature was extensively studied when a robot which mimicked the gecko’s satae was built and successfully tested out.

(a) toe pads to (b) lamellae to (c) top view and (d) side view of setal arrays to (e) spatulae. Right: Tim Sullivan

(a) toe pads  (b) lamellae (c) top view and (d) side view of setal arrays (e) spatulae. Right: Tim Sullivan

The gripper adhesive might not be as intricate as a gecko’s foot but it works in much the same way as tests showed at JPL in Pasadena, Calif. but also in zero-G on NASA’s reduced-gravity airplane. Like a gecko’s foot, it is only sticky if the flaps are pushed in a specific direction but making it stick only requires a light push in the right direction. This is a helpful feature for the kinds of tasks a space gripper would perform.

Some of the gripped test objects weighed as much as 800 pounds, as described in the journal Science Robotics. Essentially, the gripper can grab both flat and round objects with a mere gentle tap and release these objects with the push of a button. It’s exactly this sort of feature that might prove essential to tackling space junk which often spin or move erratically, and their surfaces can be relatively smooth and hard to grasp.

“Only when you load it in a certain direction does it suddenly adhere, and when you relax that force it comes right off,” Cutkosky told CNN Tech. “That really is the secret to it.”

“If I came in and tried to push a pressure-sensitive adhesive onto a floating object, it would drift away,” said Elliot Hawkes, MS ‘11, PhD ‘15, a visiting assistant professor from the University of California, Santa Barbara and co-author of the paper. “Instead, I can touch the adhesive pads very gently to a floating object, squeeze the pads toward each other so that they’re locked and then I’m able to move the object around.”

The geck-inspired robotic gripper grabbing a cube on a parabolic flight. Credit: Stanford.

The geck-inspired robotic gripper grabbing a cube on a parabolic flight. Credit: Stanford.

Now, the team hopes to finally set their gripper in a live environment, in space. But first, they need to retrofit their current prototype to match the challenges of space, like inhumanly cold temperatures. If all works as planned, the team envisions two types of grippers getting deployed in orbit. One would a be a 2,000-pound satellite that sweeps its orbit grabbing and relocating debris so they burn up in the atmosphere while another option is a tiny satellite no heavier than a few pounds that would clean debris one piece of junk at a time. The latter option would be cheaper to build and fly — a swarm of such objects could be deployed, though there’s a risk these too could become space junk if we’re not careful.

Beyond space junk, a gripping robotic arm could be useful aboard the International Space Station too. Many dangerous missions which require astronauts taking space walks could be superseded by a geck-like arm.

“The other area of interest is to have small robots that could climb around the outside of a space station or other structure without floating off because they stick using these adhesives. That would be to do inspection or maintenance,” Cutkosky said.

Your robot always dropping stuff? Try these gecko-inspired pads

Researchers have created a new family of grippers inspired by the gecko’s ridiculously adhesive toes. These pads could be used to improve object handling on the production line or allow robots to better interact with the world.

Gecko gripper.

The gripper holding a flask of orange juice.
Image credits Sukho Song.

It’s easy to take gripping for granted, but when you really think about it (or have a robot to compare yourself with) it’s an amazing and complex skill. Our brains and bodies make it look easy — after all, even a small child knows how to handle all kinds of objects. But the number of minute processes that go on in the background, even for the simplest of gripping motions, is staggering.

Handle with care

Without even thinking about it, you know much force to apply to grip an object but not break it, how to calibrate your emotions so you’ll bring the cup to your lips — not throw it to at the ceiling. But if you want to make a robot do the same thing, you’ll have to go through a lot of programming and trial and error.

Looking for a simpler way to help our digital friends get a grip on life, researchers have done a bit of biomimicry and copied the working principles of the gecko‘s toes. The resulting pads should help address many of the problems machines today have in manipulating objects and should allow them to navigate a much wider range of shapes and materials — such as irregularly shaped walls or ceilings and slippery metal surfaces.

Gecko’s toes can stick to anything using Van der Waals forces. Long story short, because some atoms and molecules tend to be polarized (having a positive-charged side and an opposing negative-charged side) they also tend to push or pull at each other like really tiny magnets. But if there’s enough of them, the forces can stack up to an impressive effect. The gecko’s toes are covered with tiny hair-like strands which increase the surface contact between them and the surface, maximizing the Van der Waals effect and allowing the lizard to walk upside down if it so desires.

Gecko Upside Down.

Rub my belly.
Image credits Wikimedia user Tolbunt5.

Previous research on this subject has resulted in synthetic microfiber arrays which replicate the gecko’s sticky toes, but imperfectly. The hook is that properly sticking these materials to a surface takes pressure meaning they have to be mounted on a rigid backing. Doing this, however, prevents the arrays from adhering to curved surfaces.

The FAM family

The new paper details how this issue can be solved by placing the microfibers on a thin, stretchy membrane to create a family of materials the researchers call fibrillar adhesives on a membrane (FAM), and developing a new kind of backing for the membranes.

For their gripper, the team used a FAM to cover one end of a shallow rubber funnel some 18 millimeters across. The other (narrow) end of the funnel was connected to an air pump, and after the FAM came in contact with the surface-to-be-held, all the air was sucked out of the funnel to flatten it onto any shape.

Testing revealed that a gripper with the contact area of only 2.5 square centimeters (roughly the size of a dime) could lift more than 300 grams (slightly less than your average can of soda). It could grip a coffee cup from the outside (convex shape), the inside (concave shape) or the handle (complex shape). It also has a light touch — the gripped could lift a cherry tomato without damaging it, and a plastic bag without ripping it. Inflating the gripper is all that’s needed to release the objects.

The technology could be used in manufacturing to shuttle delicate or complex-shaped components around, or in medicine to grip organs without damaging them. Alternatively, they would give robots enough grip to climb onto planes, ships, or reactors to perform maintenance and repairs.

But before we start seeing them used on a wide scale, researchers have to ensure that the grippers are durable enough to withstand hundreds of thousands of usage cycles, see how they scale up to grip heavier loads and make them economically viable in comparison to simple clamps or suction cups.

The team says that scaling the grippers up to a few tens of centimeters so they can lift heavy objects — but they’re still testing on durability.

The full paper “Controllable load sharing for soft adhesive interfaces on three-dimensional surfaces” has been published in the journal PNAS.

Each scale is the design of a fingernail. Credit: Mark D. Scherz and Juan D. Daza.

Newly discovered ‘escape artist’ gecko species evades predators by shedding its scales

Each scale is the design of a fingernail. Credit: Mark D. Scherz and Juan D. Daza.

Each scale is the size of a fingernail. Credit: Mark D. Scherz and Juan D. Daza.

A new gecko species from Madasgar employs a unique strategy to evade predators. When a predator such as a snake strikes the gecko, it’s not dinner he’s getting but a mouthful of scales.

A handy, detachable body armor

Mark Scherz. Credit: Perj Blog.

Mark Scherz. Credit: Perj Blog.

Geckolepis megalepis probably has the largest body scales of any gecko. This is no coincidence — the animal evolved in such a manner to make it easier to remove the armor. The larger the surface area of the scale, the easier it is for the scales to come off, like a glove off the hand. Once the scales are pulled off, however, the gecko is totally naked and exposed, revealing its pink, shiny skin.

Mark Scherz, a herpetologist at the Bavarian State Collection for Zoology in Munich, and colleagues say removing the scales doesn’t produce any visible scarring. In a matter of weeks, the gecko is able to regenerate its lost scales as if nothing happened, as reported in PeerJ.

“This regeneration is, as far as we have been able to tell, scarless, and the resulting regenerated scales are indistinguishable from original ones,” said Scherz for the Washington Post. “That is not the case of many other geckos, in which the regenerated scales have a distinctly different appearance to the original ones.”

Credit: Frank Glaw.

Credit: Frank Glaw.

G. megalepis can shed its scales lightning fast, and it doesn’t take a bite either. When researchers tried to capture it with cotton pads, the gecko immediately shed its armor. They eventually managed to capture a specimen with the scales intact using plastic bags.

“I just also want to highlight the fact that the lengths that animals can go to in order to escape predation are incredible. These geckos have the largest scales of any species, which, far from rendering them more protected, we think makes them particularly easy to lose. But what these geckos drop are not just scales, but skin as well! And just like the tail, it is also partially voluntary. The kind of evolutionary pressure that would cause that degree of adaptation is hard to imagine, but we know of few examples of animals that are better adapted to escape from would-be predators in a more extreme way,” Scherz said in an interview.

Stereo image of Geckolepis. Credit: Mark Scherz

Stereo image of Geckolepis. Credit: Mark Scherz

There’s a lot we can learn from this crafty gecko. The German researchers made CT scans of the reptile’s body and they hope this information can one day provide valuable insights. Such information, for instance, could be useful in the field of medicine for accelerating human skin healing.

Gecko feet may help keep art clean

Geckos may be giving art conservationists an unexpected hand – a new way of keeping art clean.

Close-up of the underside of a gecko’s foot as it walks on vertical glass. Image via Wikipedia.

This doesn’t mean we’ll be letting hordes of geckos run rampant through the Louvre because that’s not how science works (though it could create a lovely Disney scene). Instead, researchers took inspiration from geckos, designing a material that can collect the smallest motes of dust from a painting without damaging it. Needless to say, this could be very useful.

“Acrylic paints are incredibly porous, so anything you’re putting on the surface could get into the pores, and then work from the insides of the pores to soften the paints,” Cindy Schwartz, an art conservator at Yale said.

Dust is a very big problem when it comes to paintings. If dust paintings are bigger than 10 micrometers, you can remove them without big problems, usually through some type of jet. But even so, there is a risk of damaging the painting, and if they’re smaller, it gets even more difficult. There are other removal methods, some more complex than others, but all have their drawbacks.

This new solution could be deceptively simple. Hadi Izadi, a postdoctoral associate and the paper’s lead author, created a material which looks much like an ordinary plastic sheet but is actually a non-sticky, elastic polymer called polydimethylsiloxane (PDMS).

Microscopic image of silica dust particles lifted by micropillars, 50 micrometers in diameter. (Credit: Vanderlick Lab)

If you would look at PDMS under a microscope, it looks like a sheet with millions of columns; there are different sizes of columns for different sizes of dust specs. Interestingly, gecko feet are designed specifically to not have things stick to them – and this is why this material is so good. It has almost no interaction with the substrate (the painting), but if their size is just right, it produces enough electrostatic energy to attract the dust specs. Therefore, it can clean the paintings without damaging the painting at all.

“Dust is something at the nanometer level,” Vanderlick says. “And there’s a lot of interesting thin film, surface, and interfacial physics associated with the preservation of art.”

Journal Reference: Removal of Particulate Contamination from Solid Surfaces Using Polymeric Micropillars.

These ancient lizards trapped in amber will help researchers patch up the incomplete fossil records. Image: David Grimaldi

Oldest chameleon-like lizard found trapped in 100 million-years-old amber

The fossil record abounds with specimens of large animals, but seem to be discriminate against squishier, soft-bodied ones. That’s because fragile bones, let alone tissue, are more vulnerable to the elemental erosion, hence difficult to preserve. New specimens trapped in amber are always a treat for scientists. Usually, you can not only discern a complete skeleton, but also soft tissue like skin or even insect wings. Recently, a treasure trove of a dozen ancient lizards trapped in amber came to scientists’ attention. Everyone was impressed by the pristine preservation, but what particularly caught their eyes was a chameleon-like creature that’s 100 million years old. That’s 78 million years older than the previous record holder.

These ancient lizards trapped in amber will help researchers patch up the incomplete fossil records. Image: David Grimaldi

These ancient lizards trapped in amber will help researchers patch up the incomplete fossil records. Image: David Grimaldi

Initially discovered in a Burmese mine, the fossils remained in private collections until a recent donation to the American Museum of Natural History. Edward Stanley of the University of Florida and colleagues used a micro-CT scanner to image all the fossils trapped in the mid-Cretaceous amber. This allowed the researchers to build complete 3D models of each specimen without actually cutting open the amber.

“These fossils tell us a lot about the extraordinary, but previously unknown diversity of lizards in ancient tropical forests,” Stanley said.

“The fossil record is sparse because the delicate skin and fragile bones of small lizards do not usually preserve, especially in the tropics, which makes the new amber fossils an incredibly rare and unique window into a critical period of diversification.”

The preservation is mind-blowing. Complete specimens were found with all limbs intact, including claws, toepads, teeth, even perfectly intact coloured scales.

These small tropical lizards offer a glimpse into the mid-Cretaceous tropical life. The findings suggest that life in the tropical forest was just as diverse as it is today.

The ancient chameleon relative. Credit: David Grimaldi

The ancient chameleon relative. Credit: David Grimaldi

A dime-sized relative of the modern chameleon was among these animals. The juvenile had ballistic tongues, suggested by the presence of the same bone found in modern chameleons,  but had not yet developed the claw-like fused toes used today to cling to branches. Interestingly, one of the geckos trapped in the amber  already evolved its famous sticky pads which can adhere to virtually any surface.

A 3-D print of a gecko trapped in the same amber. Using CT scans, then printing the models allows researchers to investigate records in greater details -- all without risking ruining the delicate fossils themselves. Image: Florida Museum of Natural History

A 3-D print of a gecko trapped in the same amber. Using CT scans, then printing the models allows researchers to investigate records in greater details — all without risking ruining the delicate fossils themselves. Image: Florida Museum of Natural History

It is thought, based on genetic screenings, that chameleons split from an ancestor called  agamidae sometime around the mid-Cretaceous, but fossils were lacking to support this hypothesis. Stanley says that the newly found chameleon-like lizard challenges the notion that these animals originated from Africa.

According to the  SSC Chameleon Specialist Group (CSG), a third of the world’s chameleon species are threatened with extinction.

“These exquisitely preserved examples of past diversity show us why we should be protecting these areas where their modern relatives live today,” Stanley said.

“The tropics often act as a stable refuge where biodiversity tends to accumulate, while other places are more variable in terms of climate and species. However, the tropics are not impervious to human efforts to destroy them.”

Findings appeared in Science Advances.

Spider-Man

Sorry to burst your bubble, but this is why you’ll never be Spiderman

Geckos are the largest animals able to scale walls. They use the same mechanism as spiders and hundreds of other animals able to do so:  through tiny hairs on their pads that adhere to surfaces due to molecular force interactions. But why isn’t there an animal bigger than the gecko that can cling to windows and walls? For that matter, why isn’t there any Spiderman? Some scientists, inspired by the gecko, are working on artificial sticky pads that might make robots and gadget-enable humans to scale walls. A new research seems cast doubt that any of this will ever work. The findings suggest that there’s an inherent trade off between size and the ability to cling to surfaces. If you’re too big, sticky pads simply don’t work. The researchers calculated that a human would need sticky pads covering 40% of our bodies or sport US size 114 feet to walk up a wall like the fabled Spiderman.

Spider-Man

Sticky pads

A typical jumping spider has small hairs that cover its feet, and each of these small hairs is covered in even smaller hairs called “setules”. One spider has more than 600,000 such setules, helping it grip surfaces with a force greater than 170 times its own weight. This force is called van der Waals force —  a form of attraction which only works between the positive and negative charges of individual molecules that are within a few nanometers of one another. The triangular-tipped setules on spiders’ feet are perfectly designed to take advantage of the van der Waals force because they form hundreds of thousands of flexible contact points. What’s cool about this type of molecular interaction is that’s dynamic. It’s not glue, and consequently not affected by the surface or the surrounding environment, which is why scaling oily or wet surfaces is easy for these animals.

Setae on the bottoms of their feet (right) help spiders stick to ceilings. Image: University of Oxford

Setae on the bottoms of their feet (right) help spiders stick to ceilings. Image: University of Oxford

Dr David Labonte and his colleagues in the University of Cambridge’s Department of Zoology studied the weight and footpad size of 225 climbing animal species including insects, frogs, spiders, lizards and even a mammal. The animals included in size had pads which were up to seven orders of magnitude spaced apart or analogous to the difference in weight between a cockroach and the Big Ben.

(a) toe pads to (b) lamellae to (c) top view and (d) side view of setal arrays to (e) spatulae. Right: Tim Sullivan

(a) toe pads to (b) lamellae to (c) top view and (d) side view of setal arrays to (e) spatulae. Right: Tim Sullivan

Though both gecko and spider use the same adhesive mechanism, the difference in the size of their pads is roughly that of the size between an ant and a human. This ratio proved to matter in how efficient animals could scale walls, the researchers found. For instance, tiny mites use approximately 200 times less of their total body area for adhesive pads than geckos.

The foot of the jumping spider Euophrys frontalis, showing the paired claws and adhesive pads. Credit: Copyright Wolff

The foot of the jumping spider Euophrys frontalis, showing the paired claws and adhesive pads.
Credit: Copyright Wolff

“As animals increase in size, the amount of body surface area per volume decreases — an ant has a lot of surface area and very little volume, and a blue whale is mostly volume with not much surface area” explains Labonte.

“This poses a problem for larger climbing species because, when they are bigger and heavier, they need more sticking power to be able to adhere to vertical or inverted surfaces, but they have comparatively less body surface available to cover with sticky footpads. This implies that there is a size limit to sticky footpads as an evolutionary solution to climbing — and that turns out to be about the size of a gecko.”

“Our study emphasises the importance of scaling for animal adhesion, and scaling is also essential for improving the performance of adhesives over much larger areas. There is a lot of interesting work still to do looking into the strategies that animals have developed in order to maintain the ability to scale smooth walls, which would likely also have very useful applications in the development of large-scale, powerful yet controllable adhesives,” says Labonte.

What’s impressive is that most of these different animals — geckos, spiders, insects, frogs etc — independently developed their sticky pads, a prime example of convergent evolution. In other words, they found the same solution to the same problem. It must be a very good solution.

It’s important to note that not all pads are the same. In some species, pad size didn’t increase to match body size, but somehow these still stuck. The obvious explanation is that these animals evolved stickier pads.

“Across all species the problem is solved by evolving relatively bigger pads, but this does not seem possible within closely related species, probably since there is not enough morphological diversity to allow it. Instead, within these closely related groups, pads get stickier. This is a great example of evolutionary constraint and innovation.”

In 2014, Stanford engineers showed off a pair of  gecko-inspired hand pads strong enough to pull the weight of an adult man and to allow him to climb a wall. However, they used adhesive materials — not specially crafted materials that could use van der Waals.

Reference: Labonte, D et al. Extreme positive allometry of animal adhesive pads and the size limits of adhesion-based climbing. PNAS, January 2016 DOI: 10.1101/033845

Geckos can run just as easily along a wall or ceiling as they can across a floor. This is due to special pads on their toes, which can even grip glass. No man-made adhesive technology comes even close to functioning as well as gecko feet. Credit: Institute for Creation Research

Gecko-hand-gloves helps human climb wall like spiderman

Watch out, Spiderman! Stanford engineers recently demonstrated a pair of  gecko-inspired hand pads strong enough to pull the weight of an adult man and to allow him to climb a wall.

Scaling walls like a gecko

Geckos can run just as easily along a wall or ceiling as they can across a floor. This is due to special pads on their toes, which can even grip glass. No man-made adhesive technology comes even close to functioning as well as gecko feet. Credit: Institute for Creation Research

Geckos can run just as easily along a wall or ceiling as they can across a floor. This is due to special pads on their toes, which can even grip glass. No man-made adhesive technology comes even close to functioning as well as gecko feet. Credit: Institute for Creation Research

At the center of the gecko’s clinging ability are its specialized pads, located on the reptile’s toes, comprised of various satae (bristle- or hair-like structures ) on the tip of which lie tiny structures called spatulae, each less than a micron wide. These allow attraction forces called van der Waals interactions to arise between the adhesive setae and the surface. A single spatulae shows very weak molecular forces, however when coupled together in thousands of thousands on the satae, the attraction becomes very strong.

gecko climb

Credit: Stanford University

Inspired by the gecko, Stanford researchers led by Mark Cutkosky designed, created and tested out various types of artificial adhesives that could copy the high surface area of the setae on a gecko’s feet. After many, many failed attempts, the team finally found the right mix: an adhesive system made from a silicone material called polydimethylsiloxane (PDMS) that is layered as microscopic wedge. The biggest challenge was making the pads have “controllable adhesion”, so they could easily be switched on or off simply by transferring weight on the adhesive. Ultimately, the researchers were able to scale their designs on hand-sized pads that helped a 70kg male human scale a smooth vertical surface.

[RELATED] Gecko sex in space, and why this is useful for science

The pads could prove useful in manipulating huge solar panels, displays or other massive objects without any help from suction power or chemical glues. Perhaps, they might be most useful in space where astronauts could cling to surfaces of the Internationals Space Station, telescopes or satellites. The pads were reported in a paper published in the journal  Journal of the Royal Society Interface.

space-gecko

Gecko sex in space, and why this is good for science

space-geckoOn July 19, the Russian space agency, Roscosmos, sent five geckos in space in order to study their sex lives under micro-gravity conditions. Five days later, though, contact with the gecko love satellite was interrupted stirring a bit of panic. Luckily, technicians managed to restore contact with the craft, according to the Russian space agency and the experiment is continuing as planned on its two-month mission.

The four females and one male will be followed by researchers as they mate, lay eggs and hatch younglings to see how micro-gravity affects fertility. Specifically, the Gecko-F4 mission aims:

  • Create the conditions for sexual activity, copulation and reproduction of geckos in orbit
  • Film the geckos’ sex acts and potential egg-laying and maximise the likelihood that any eggs survive
  • Detect possible structural and metabolic changes in the animals, as well as any eggs and foetuses

As if enough eyes weren’t enough, the geckos will be kept company by Drosophila fruit flies, as well as mushrooms, plant seeds and various microorganisms that are also being studied. In the chamber next to this tiny ecosystem lies a furnace were melting and solidification of metal alloys in space will be studied. After the two month study is over, Roscosmos plans on running addition experiments before its eventual Earth uncontrolled re-entry four months later.

[ALSO READ] Gecko-like robot climbs walls effortlessly

This, of course, assuming contact isn’t lost again. The Russian space agency was quoted saying the most probable cause of the initial communications failure may have been space debris. The satellite that carries the experiment is flying in low-orbit at around 357 miles away from the Earth’s surface. Here, the gecko ferrying satellite shares orbit with the International Space Station and around 20,000 space debris. We’ve written extensively in the past on the dangers space debris pose to space missions and how we might possibly tackle them.

If mankind is ever to become an interstellar race, some humans will most certainly spend their lifetimes in space. Trips might last for whole generations in fact. It becomes thus important to understand what kind of effects zero gravity has on mating and fertility. If, for instance, across many generations maybe, it’s found that humans can’t reproduce in space this would spell a disaster. Geckos are part of a bigger plan meant to probe this very important question. They’re not the first beings to mate in space, though. This honor belongs to a cockroach!

In 2007, Roscosmos sent a crew of geckos, newts, snails, Mongolian gerbils and cockroaches to space and landed the experiment back on Earth 12 days later. The cockroaches were the first to mate in space, and researchers were able to identify which of them was the first to conceive in space – a cockroach named Nadezhda, which means “hope” in Russian. Interestingly enough, the roaches “run faster than ordinary cockroaches, and are much more energetic and resilient”, according to Russian researchers.

gecko-leaf

Gecko clinging ability on wet surfaces might inspire water-resistant adhesive tape

The gecko is a phenomenal reptile which has always amazed observers, and especially scientists, thanks to its remarkable ability to cling to surfaces. Though they’ve been studied for a while now, it’s only recently that researchers have learned how geckos scale across wet surfaces, like leaves and trees found in its natural tropical environment. The discovery might find its use in a variety of applications. For instance, a tape that works even in wet environments based on a gecko-design might finally arrive; something I’m sure a lot of you have been waiting for a long time, especially those of you who like to fix just about anything with tape.

gecko-leaf

At the center of the gecko’s Spider Man-like clinging ability are its specialized pads, located on the reptile’s toes, comprised of various satae (bristle- or hair-like structures ) on the tip of which lie tiny structures called spatulae, each less than a micron wide. These allow attractive forces called van der Waals interactions to arise between the adhesive setae and the surface. A single spatulae shows very weak molecular forces, however when coupled together in thousands of thousands on the satae, the attraction becomes very strong. These forces are so strong that they not only allow for supporting the gecko’s weight, but for even a highly roboust human as well –  up to 133 kg can be sustained by the adherence forces between the gecko’s toes and a surface. This feature was extensively studied when a robot which mimicked the gecko’s satae was built and successfully tested out.

However, this all has been well known for some time, what scientists have been having a hard time with is understanding how the gecko climbs wet surfaces. University of Akron researchers set out to find out and eventually succeeded after they carried extensive tests. Six tokay geckos (Gekko gecko) were harnessed and instructed to climb on four different types of surfaces that varied in their degree of water resistance: glass, plexiglass, a transparent plastic often used as a glass alternative, and Teflon.

To measure the animal’s grip for each type of surface, a force in the opposite direction of the gecko’s movement was applied until it slipped .On surfaces with low wettability, like plexiglass and the transparent plastic, the areas in contact with the gecko’s foot stay dry, maintaining an excellent level of adhesion. These materials mimic the surface chemistry of the leaves geckos are really walking on in their natural environments,  the researchers say.

On glass, which has a high wettability, a film of water developed between the geckos’ toes and the surface, reducing their ability to stick to the glass. These findings suggest the impact of water on adhesive strength correlates with the ability of a liquid to keep contact with a solid surface (wettability).

The researchers hypothesize that the gecko’s evolved its sticky pads that allows it to cling on wet, yet tractable tropical leaves in order to escape predators, even when the environment became wet, which is ever so often in its homeland. A synthetic tape that works in wet environments would be a dream come true for any do it yourself aficionado out there, and one based on the gecko’s pads design might soon be attempted.

The findings were reported in a paper published in the journal Proceedings of the National Academy of Sciences.

An Agama lizard next to the Tailbot, a robot that can automatically adjust its position to pitch-forward, similar to the way the lizard uses its tail. (c) Robert Full lab, UC Berkeley

Leaping lizard tails could provide massive advances in robotics


Researchers at Berkley University have developed an extraordinary robotic toy car called the “Tailbot”, equipped with a stabilizing tail, which is able to correct and adjust its position during mid-air leaps to land safely. The biologists and engineers involved in the study were inspired by lizards that swing their tails upward to prevent them from pitching head-over-heels into a rock.

From Jurassic Park to Lizards

The research initially sprung after studying a 40 year old hypothesis that that the two-legged theropod dinosaurs used their tails to stabilize during their long and high leaps, assisting them in hunting or running away from predators through various obstacles. When one of the researchers involved in the study noticed how a lizard recovered masterfully after a slip, it immediately became clear that the animal might become the perfect subject for testing the value of a tail.

Thus, the team of researchers lead by Professor Robert Full , used a red-headed African Agama lizard, which they coaxed into moving through a layout comprised of various degrees of traction, from slippery to easily-gripped. All of the lizard’s movement through the platform was documented with a high-speed camera which allowed the researchers to perceive even the slightest movements of the tail.

When the lizard reached the final stage of the platform, towards which it had to jump on a wall on top of which was a shelter, it slipped because of the low-traction, control surface. During the fall, the lizard began to spin out of control, however within an instant its tail counteracted the spin for it to land perfectly, limbs forward.

By studying the various angles and position of the lizard’s tail, the researchers managed to build an accurate mathematical model, which was incorporated in the Tailbot – a contraption that looks more like a toy car, but which is a lot more powerful than you might think.

“We showed for the first time that lizards swing their tail up or down to counteract the rotation of their body, keeping them stable,” says team leader Robert J. Full, professor of integrative biology, who reports findings in the journal Nature.

“Inspiration from lizard tails will likely lead to far more agile search-and-rescue robots, as well as ones having greater capability to more rapidly detect chemical, biological, or nuclear hazards.”

During a demonstration of the Tailbot with its tail feedback sensors turned off, it took a nose-dive for a head on, catastrophic collision. When the gyroscopically controlled tail was switched on and positioned for a nose-dive, it automatically righted itself in midair.

An Agama lizard next to the Tailbot, a robot that can automatically adjust its position to pitch-forward, similar to the way the lizard uses its tail. (c) Robert Full lab, UC Berkeley

An Agama lizard next to the Tailbot, a robot that can automatically adjust its position to pitch-forward, similar to the way the lizard uses its tail. (c) Robert Full lab, UC Berkeley

The Tailbot was developed by Thomas Libby and fellow mechanical engineering graduate student Evan Chang-Siu, who presented their paper last October’s meeting of the International Conference on Intelligent Robots and Systems, were they were one of five finalists there among more than 2,000 robot studies.

A robot that could save lives

Applications for the Tailbot could be numerous. Search and rescue bots that can easily move and leap through obstacles in a disaster zone might prove to be life saving. Robot design stuck within anthropomorphic design barriers will definitely be replaced by more suitable robots that can crawl, race and dangle in the future.

“This is very, very novel,” Murphy said, describing both the discovery that a tail is critical for next-generation robot design and in modeling nature to program how robots move.

And she expects the pace of research, particularly mimicking animal movement in robotics, will lead to an explosion of innovation in the coming decade. Just imagine having a robot that can effectively combine the mimicking of a gecko’s climbing toe hairs and its stabilizing tail.

“I think in 10 years when you turn on CNN and there’s a disaster, if you don’t see a robot in there you’ll be thinking, ‘What’s up with that?’ ” Murphy said. “They’re going to be so common.”

 

via futurity

Close-up of the underside of a gecko's foot as it walks on vertical glass. (c) Wikicommons

Gecko-like robot climbs walls effortlessly

Close-up of the underside of a gecko's foot as it walks on vertical glass. (c) Wikicommons

Close-up of the underside of a gecko's foot as it walks on vertical glass. (c) Wikicommons

The gecko is one of the most fascinating lizards, because of its feet’s unique ability of dry adherence to solid surfaces allowing it to surmount any geometry and making it an excellent climber in the process. Unlike other animals which employ a liquid or some kind of suction to climb walls, the gecko uses inter-molecular attraction forces known as van der Waals. Scientists have made numerous attempts of mimicking this extremely complex, yet  potentially useful, feature. Recently, a demonstration comprised of a tank-like robot that can climb smooth walls with the ease of a gecko on a moon-light night shows that scientists are only a step away from building the perfect escalatting bots.

On its toes, the gecko exhibits specialized pads comprised of various satae (bristle- or hair-like structures ) on the tip of which lie tiny structures called spatulae, each less than a micron wide. These allow attractive forces called van der Waals interactions to arise between the adhesive setae and the surface. A single spatulae shows very weak molecular forces, however when coupled together in thousands of thousands on the satae, the attraction becomes very strong. These forces are so strong that they not only allow for supporting the gecko’s weight, but for even a highly roboust human as well –  up to 133 kg can be sustained by the adherence forces between the gecko’s toes and a surface. Impressed yet?

The Canadian scientists of Mechanisms ‘N Robotics for Viable Applications (MENRVA) Lab at Simon Fraser University in Burnaby, British Columbia, were impressed enough to begin a laborious research. The robot team, led by Jeff Krahn at Simon Fraser University in Burnaby, recreated the gecko toe pads by using a  material called polydimethysiloxane (PDMS) for the satae, which they made 17 microns across and with ends shaped like mushroom caps. The structured adhered easily enough to a surface, however for the robot to move it had to peel off the attraction forces, otherwise it would get stuck. This is why Krahn and his team put the mushroom-capped setae on tank-like treads.

“While van der Waals forces are considered to be relatively weak, the thin, flexible overhang provided by the mushroom cap ensures that the area of contact between the robot and the surface is maximized,” Krahn explained in a news release.

By using the gecko-like toe pads, the researchers’ robot was able to climb even smooth surfaces such as glass or plastic, materials that are a consistent challenge for robots that use magnets, suction cups, spines and claws to climb. In addition the later various types of robots offer other difficult issues, like gooey trails or special conditions (magnets need metal, claws need something to stick to, suction cups need powerful pumps and so on).

A wet adhesive machine leaves traces of its movement, and usually its main mode of failure is due to it being clogged by dust particles that stick onto these tracing layers.

The tank-like robot, dubbed  Timeless Belt Climbing Platform (TBCP-II),  weighs in at 240 grams and can transfer from a flat surface to a wall over inside and outside corners. It has a top speed of 3.4 centimeters per second. To detect its surroundings and alter its course to navigate obstacle, the robot has built in sensors, however its makers are now working hard to improve its control strategy to eventually render it fully autonomous.

Mike Murphy, now at Boston Dynamics (the company that brought us The Petman), has done extensive research on dry adhesion in robots. He said the fact that the Simon Fraser team was able to make a tread is something of a first. “Creating a continuous loop of micropatterned adhesive can be a challenge,” he said. “Accomplishing internal and external transitions is a difficult maneuver for any climbing robot, but the reward is significantly improved applicability in real-world environments.”

source

Gecko tail has a mind of its own

geckoThe (awesome) ability of geckos and other related reptiles to shed their tale when endangered by predators has been known for a long time, but scientists know little about the movement, and especially what controls the movement of the tail once it’s separated from the tail. Anthony Russell of the University of Calgary and Tim Higham of Clemson University in South Carolina put a lot of time and effort into solving this mystery.

What’s interesting is that after it separates from the body, the tail does not only have rhythmic movement, but also flips, jumps and lunges, exhibiting a complicated movement pattern. Studying and understanding this behavior could be extremely useful for further spinal cord studies.

“Much is known about the ecological ramifications of tail loss, such as distracting predators, storing energy reserves and establishing social status but little is known about the pattern and control of movement of automized gecko tails,” says Russell a biological sciences professor at the U of C. “What we’ve discovered is that the tail does not simply oscillate in a repetitive fashion, but has an intricate repertoire of varied and highly complex movements, including acrobatic flips up to three centimetres in height.”

However, this is just the first step, and more efforts should be put into this research.

“An intriguing, and as yet unanswered, question is what is the source of the stimulus is that initiates complex movements in the shed tails of leopard geckos,” says Higham. “The most plausible explanation is that the tail relies on sensory feedback from the environment. Sensors on its surface may tell it to jump, pivot or travel in a certain direction.”

Secret of spider-man suit revealed

spider man

If you ever wanted to stroll “spidy” your way around the big city, your dream is one step closer to becoming reality, as physicists have found the formula for what they call a “spider suit“. To do this, they applied what they learned from the dazzling gecko and it’s ability to climb walls as well as using the properties of velcro.

Professor Nicola Pugna published a paper in the Journal of Physics: Condensed Matter in which he has described how adhesive forces could be used in order to create a suit that has the ability to support the weight of a human body without losing the above mentioned properties.

The suit would be covered with molecular sized hooks, which will allow whoever wears it to climb and detach easily from surfaces. These hooks will work in pair with the van der Waals forces which allow geckos to climb the way they do and hang from ceilings.

“There are many interesting applications for our theory, from space exploration and defence to designing gloves and shoes for window cleaners of big skyscrapers” said Pugno.

While shoes for window cleaners do seem a bit impractical, it’s obvious that such a development could be put to great use in quite a number of fields. It becomes even more attractive, as just as the spiders’ and geckos’ feet, these hooks are water resistant and self cleaning, which means they will not deteriorate and bad weather and dirt won’t do any harm.

This means of course that they could be used in the harshest of environments, including underwater and in outer space. But there are numerous problems that have to be solved, because the human muscles are very different from those of the gecko (really ??), and the suit has to be designed in such a way that it doesn’t cause excessive fatigue. Pugno is aware of all these things that have to be solved, but he is still very confident in this suit. He concludes

“However now that we are this step closer, it may not be long before we see people climbing up the Empire State Building with nothing but sticky shoes and gloves to support them” added Pugno.