Herbert Waite at UC Santa Barbara has been curious about mussel adhesion since the late 1970s, when he started to study the properties of how mussels stay put in their turbulent, intertidal environments. He says, “Everyone thought I was crazy. ‘Why are you working on this?’” It was purely out of curiosity he studied the properties of mussel adhesion, but now it looks like there might be a significant practical application from these studies.

Marcus Textor is a Swiss scientist who worked a lot with graduate students on biomimetic processes—where engineering can follow clues from nature. His colleague, Phillip Messersmith, has similar interests, but uses bio-inspiration for medical purposes.

Building upon Waite’s research, Messersmith is working to create a surgical adhesive. All the tissues within the human body are wet, he explains. “We have a lot to learn from the mussel” to create an adhesive that works within the human body.

The three came together with Emily Carrington at the recent AAAS meeting in Boston to discuss mussel adhesion. Carrington described how different species make different materials at different times of the year.

The materials at work in mussels are called byssus threads. They’re strong fibers or filaments that the animals secrete to attach themselves to rocks and other materials. It appears that mussels are able to remove the water from the surface as they attach and then remain attached. Waite says that they are still actively looking at how mussels perform this feat—the organism may somehow be able to convert an amino acid to a dopa to displace surface water.

Messersmith has extracted and analyzed the proteins at work here, coming up with a synthetic property that is able to perform the same trick—adhering in water. He is in the preclinical stages, experimenting with the property in animal models, before testing in humans.

Carrington has found that mussel adhesion seems to diminish in warmer temperatures. This happens in nature and varies seasonally. Might it also happen more frequently as climate warms? She is trying to answer this question in her lab. Messersmith will be very curious to find out what she discovers as he applies it to his own research.

Image: Cianke/Wikipedia

But researchers from MIT and Brigham and Women’s Hospital believe these quills could be quite helpful. They published a study this week in the Proceedings of the National Academy of Sciences describing how the quills function and how researchers might exploit the quills’ unique properties to develop new types of needles, adhesives and other medical devices.

Here’s how they work: while the quill is entering tissue, barbs covering the surface of the quill act to localize the penetration forces, allowing it to tear through tissue fibers much more easily—just as a serrated knife cuts through tomato skin far more cleanly than a straight-edged knife. When it comes to the force required for pullout, the barbs act like anchors that make it difficult to remove the quill without damaging tissue.

To create needles that enter skin more efficiently, the researchers believe the quill system could be tweaked so that it penetrates tissue easily, but also detaches easily, enabling design of less-painful needles for injections.

To explore the possibility of making stronger adhesives, the researchers created a patch with an array of barbed quills on one side. They found that the energy required to remove this patch was 30 times greater than that needed for a control patch, which had quills but no barbs.

There is a great need for such adhesives, especially for patients who have undergone gastric-bypass surgery or other types of gastric or intestinal surgery. These surgical incisions are now sealed with sutures or staples, which can leak and cause complications.

“We believe that evolution is the best problem-solver,” says co-author Jeffrey Karp of Brigham and Women’s Hospital.

The trick with most vertical or inverted walkers has to do with forces or sticky adhesives that work well on dry land, but not so much when things get wet and, well, slippery.

But two researchers, Stanislav Gorb of Kiel University in Germany and Naoe Hosoda of the National Institute for Material Science in Japan, decided to test the locomotion of Gastrophysa viridula, normally a terrestrial beetle, underwater. Ed Yong describes their submarine movements in Discover:

… once they touch the bottom, they can walk around very easily. Their footsteps aren’t precarious ones, either. While they don’t walk quite as easily underwater as they do on land, they can still produce a fair amount of force.

How are the beetles doing this? Bubbles, of course! The beetles use air bubbles trapped between their setae (the small hairs on the bottom of the beetles’ feet) to produce surface tension that creates stickiness underwater… At least for something the size of a beetle.

But wait, these bubbles probably do even more! Nature reports that

The bubbles themselves provide adhesion, but they may also de-wet the area around the beetles’ feet to allow the ‘hairs’ to function in the same way as they do in the dry.

Oils on the setae further enhance the adhesive effect.

So what next? Bio-inspired technology! Co-author Gorb explains their new environmentally-friendly, underwater adhesive, “Inspired by this idea, we have designed an artificial silicone polymer structure with underwater adhesive properties.” Microscopic bristles keep air trapped in the material, mimicking the beetles’ bubbles, keeping the material sticky underwater without using glue. Good ideas stick!

Images: Stanislav Gorb and Naoe Hosoda

Among their subjects are geckos and cockroaches. “Cockroaches continue to surprise us,” says Full, a professor of integrative biology who 15 years ago discovered that when cockroaches run rapidly, they rear up on their two hind legs like bipedal humans. “They have fast relay systems that allow them to dart away quickly in response to light or motion at speeds up to 50 body lengths per second, which is equivalent to a couple hundred miles per hour, if you scale up to the size of humans. This makes them incredibly good at escaping predators.”

Besides their speed to evade predators, cockroaches are also able to flip under ledges and disappear in the blink of an eye, the UC Berkeley researchers report recently in PLoS ONE. The cockroach does this by grabbing the edge with grappling hook-like claws on its back legs and swinging like a pendulum 180 degrees to land firmly underneath, upside down.

This pendulum swing subjects the animal to 3-5 times the force of gravity (3-5 gs), similar to what humans feel at the bottom of a bungee jump, lead author Jean-Michel Mongeau says.

(Video of the feat is available here.)

Surprisingly, the researchers observed geckos using this same escape technique both in the lab and in the rain forest at the Wildlife Reserves near Singapore.

“This behavior is probably pretty widespread, because it is an effective way to quickly move out of sight for small animals,” Full says.

Full and his colleagues make good with these obsessions with animal movements. They use the mechanics found in nature for robotics. Nature has had millions of years to develop the engineering, so why not borrow it?

“This work is a great example of the amazing maneuverability of animals, and how understanding the physical principles used by nature can inspire design of agile robots,” UC Berkeley engineering professor Ron Fearing says.

With the help of Poly-PEDAL Lab’s observations, Fearing’s team created a robot that can turn onto ledges like the roaches and geckos.

This new robot could help in dangerous search and rescue missions, according to Full. “That’s really the challenge now in robotics: to produce robots that can transition on complex surfaces and get into dangerous areas that first responders can’t get into.”

Photo by Jean-Michel Mongeau and Pauline Jennings, courtesy of PolyPEDAL Lab, UC Berkeley

Constructed from a set of smart materials—which have the ability to change shape or size as a result of a stimulus—and carbon nanotubes, Robojelly is able to mimic the natural movements of a jellyfish.

The jellyfish is an ideal invertebrate to inspire vehicle design due to its simple swimming action: it has two prominent mechanisms known as “rowing” and “jetting.”

A jelly’s movement is  dependent upon circular muscles located on the inside of the bell– the main part of the body, shaped like the top of an umbrella. As the muscles contract, the bell closes in on itself and ejects water to propel the jellyfish forward. After contracting, the bell relaxes and regains its original shape.

Robojelly is powered by heat-producing chemical reactions between the oxygen and hydrogen in water and the platinum on its surface. The heat given off by these reactions is transferred to the artificial muscles of the robot, causing them to transform into different shapes.

This green, renewable element means Robojelly can regenerate fuel from its natural surroundings and therefore doesn’t require an external power source or the constant replacement of batteries.

The researchers see Robojelly’s future in underwater search and rescue operations. The technology is published in today in Smart Materials and Structures.

ScienceNOW reports that:

Tails are often an enigma; many creatures have them, but scientists know little about their function, particularly for extinct species. Dinosaur tails are no exception. Researchers have speculated that some species’ tails were used in fighting, whereas others for stability.

Our friend Robert Full and his colleagues at UC Berkeley found how when leaping, red-headed African Agama lizards swing their tails upward to prevent them from pitching head-over-heels into a rock. You can see a video of this feat here.

“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 Full. “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.”

While Full is a biology professor, he is no stranger to robots, Scientific American reports.

These are just the latest developments in Full’s full-on flirtations with robots. He has worked with engineers since the mid-1990s when he helped to develop the crab-inspired Ariel, a minesweeping robot… that can look for buried explosives in surf zones. In 2008 Full co-founded the Center for Integrative Biomechanics in Education & Research (CiBER) at University of California, Berkeley, to further integrate the work of biologists and engineers when designing technology.

“Engineers quickly understood the value of a tail,” UC Berkeley engineering graduate student Thomas Libby explains. “Robots are not nearly as agile as animals, so anything that can make a robot more stable is an advancement, which is why this work is so exciting.”

Full and his team received a surprise benefit from the lizard tail research: understanding how dinosaur tails function.  The new research tested a 40-year-old hypothesis that the two-legged theropod dinosaurs—the ancestors of birds—used their tails as stabilizers while running or dodging obstacles or predators.

Indeed, just like the velociraptor depicted in the movie Jurassic Park, these agile dinosaurs may also have used their tails as stabilizers to prevent forward pitch, Full says. “Muscles willing, the dinosaur could be even more effective with a swing of its tail in controlling body attitude than the lizards.”

The research is published in the recent edition of Nature.

Image: Robert Full lab, UC Berkeley

But here’s an interesting twist to the tale. A recently designed robot at the Biomimetic Millisystems Lab at UC Berkeley is now shedding light on flight evolution.

A research team, led by Ron Fearing—we highlighted some of his early biomimicry work a few years ago here—wanted their robotic cockroach, DASH, to move faster. DASH is a lightweight, speedy robot made of inexpensive, off-the-shelf materials first launched in 2009. Its small size makes it a candidate for deployment in areas too cramped or dangerous for humans to enter, such as collapsed buildings.

But compared with its biological inspiration, the cockroach, DASH had certain limitations as to where it could scamper. Remaining stable while going over obstacles is fairly tricky for small robots, so the researchers affixed DASH with lateral and tail wings borrowed from a store-bought toy to see if that would help.

The researchers ran tests on four different configurations of the robotic roach, now called DASH+Wings. The test robots included one with a tail only and another that just had the wing’s frames, to determine how the wings impacted locomotion.

With its motorized flapping wings, DASH+Wings’ running speed nearly doubled, going from from 0.68 meters per second with legs alone to 1.29 meters per second. The robot could also take on steeper hills, going from an incline angle of 5.6 degrees to 16.9 degrees.

“With wings, we saw improvements in performance almost immediately,” says Kevin Peterson, a Ph.D. student in Fearing’s lab. “Not only did the wings make the robot faster and better at steeper inclines, it could now keep itself upright when descending.

The engineering team’s work caught the attention of animal flight expert Robert Dudley, a UC Berkeley professor of integrative biology, who noted that the most dominant theories on flight evolution have been primarily derived from scant fossil records and theoretical modeling.

He referenced previous computer models suggesting that ground-dwellers, given the right conditions, would need only to triple their running speed in order to build up enough thrust for takeoff. The fact that DASH+Wings could maximally muster a doubling of its running speed suggests that wings do not provide enough of a boost to launch an animal from the ground. This finding is consistent with the theory that flight arose from animals that glided downwards from some height.

“The fossil evidence we do have suggests that the precursors to early birds had long feathers on all four limbs, and a long tail similarly endowed with a lot of feathers, which would mechanically be more beneficial for tree-dwelling gliders than for runners on the ground,” says Dudley.

Dudley said that the winged version of DASH is not a perfect model for proto-birds – it has six legs instead of two, and its wings use a sheet of plastic rather than feathers – and thus cannot provide a slam-dunk answer to the question of how flight evolved.

“It’s still notable that adding wings to DASH resulted in marked improvements in its ability to get around,” Fearing adds. “It shows that flapping wings may provide some advantages evolutionarily, even if it doesn’t enable flight.”

Their research was published online today in the journal Bioinspiration and Biomimetics.

Image by Kevin Peterson, Biomimetic Millisystems Lab

Which leads us to the latest headline, rock and roll robots inspired by caterpillars.

Some caterpillars have the extraordinary ability to rapidly curl themselves into a wheel and propel themselves away from predators. This highly dynamic process, called ballistic rolling, is one of the fastest wheeling behaviors in nature. (You can see a great video of ballistic rolling on YouTube.)

Researchers from Tufts University saw this behavior as a way to give soft robots more speed and power. The results of their study are published today in Bioinspiration & Biomimetics.

To simulate the movement of a caterpillar, the researchers designed a 10cm long soft-bodied robot, called GoQBot, made out of silicone rubber and actuated by embedded shape memory alloy coils. It was named GoQBot as it forms a “Q” shape before rolling away at over half a meter per second.

The GoQBot was designed to specifically replicate the functional morphologies of a caterpillar, and was fitted with 5 infrared emitters along its side to allow motion tracking using one of the latest high-speed 3D tracking systems. Simultaneously, a force plate measured the detailed ground forces as the robot pushed off into a ballistic roll.

In order to change its body conformation so quickly, in less than 100 milliseconds, GoQBot benefits from a significant degree of mechanical coordination in ballistic rolling. Researchers believe this coordination is mediated by the nonlinear muscle coupling in the animals.

The researchers were also able to explain why caterpillars don’t use the ballistic roll more often as a default mode of transport; despite its impressive performance, ballistic rolling is only effective on smooth surfaces, demands a large amount of power and often ends unpredictably.

Not only did the study provide an insight into the fascinating escape system of a caterpillar, it also put forward a new locomotion strategy that could be used in future robot development. According to Science News,

Robots similar to GoQBot may someday aid in search and rescue operations that require both crawling through tight, dangerous spaces and moving across flat ground.

Image courtesy of Huai-Ti Lin

Presenting at the National Meeting of the American Chemical Society, MIT’s Daniel Nocera, PhD, announced the first practical artificial leaf.

“A practical artificial leaf has been one of the Holy Grails of science for decades,” said Dr. Nocera, who led the research team. “We believe we have done it. The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station,” he said. “One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology.”

About the shape of a poker card but thinner, the device is fashioned from silicon, electronics and catalysts, substances that accelerate chemical reactions that otherwise would not occur, or would run slowly. Placed in a single gallon of water in bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day. It does so by splitting water into its two components, hydrogen and oxygen. These two gases would then be stored in an electricity-producing fuel cell located either on top of the house or beside it.

Right now, the artificial leaf is about 10 times more efficient at carrying out photosynthesis than a natural leaf. However, Nocera is optimistic that he can boost the efficiency of the artificial leaf much higher in the future.

And that’s not all. Science Now reports:

The new catalyst also appears highly stable. Nocera says his team has been operating the device for a week, using water from the nearby Charles River in Cambridge, without any drop in efficiency. The next step is to find out whether the device works equally well in seawater. If so, it could dramatically lower the cost of producing hydrogen fuel.

Use in the real world is not so far in the future, according to Discover’s 80beats blog:

Tata Group, an Indian conglomerate, plans on creating a power plant based on this research within the next year and a half.

“Nature is powered by photosynthesis, and I think that the future world will be powered by photosynthesis as well in the form of this artificial leaf,” said Nocera.

Deal me in!

Image courtesy of Wikimedia

If Termites Can Do It, Why Can’t We?
Lakshmi Reddi, an engineer at the University of Central Florida, believes that if termites can build soil towers that maintain a constant temperature of 85 degrees Fahrenheit, we should be able to design more energy efficient buildings. Similarly, he discussed the thermoregulating properties of animal and human skin—maintaining a constant temperature within our bodies despite outside temperatures. Just looking at a teeny part—the human fingertip—scientists are able to see how “the blood flows and adjusts velocity in response to ambient temperatures,” according to Reddi. He believes this can also be applied to more efficient and sustainable building design.

Adaptive Plants
Kon-Well Wang of the University of Michigan is working with biologists to learn from plants. Plant cells are remarkable at adapting and self-healing—basically morphing as their environment demands. The research is still very basic, but Wang believes his team could build structures that do the same thing—“designed to twist, bend, stiffen and even heal themselves,” from a press release. He sees potential applications in aircraft wings (morphing and flexible like bird wings) and morphing robots.

Hair-like Sensors
Chang Liu of Northwestern University is looking at biological hair sensors. Not the hair on your head, but the hair in your ears that helps you hear, the hair on the backs of cockroaches and on the legs of spiders that help them detect movement and the hair on fish that allow them to sense water flowing around them. Liu believes that he could build better, cheaper sensors for biomedical applications or underwater vehicles. More info on his research can be found here.

Bear Metabolic Suppression
Finally, researchers in Alaska made startling discoveries when observing black bears hibernate in a lab in Alaska. The bears’ heart rates slowed, their breathing reduced to one to two times per minute, their body temperature decreased only slightly and they lost no muscle or bone mass despite the fact they were asleep for five to six months on end. What if humans could hibernate like this? Craig Heller, one of the authors of the paper in Science told NPR:

…for people bedridden for long periods, or who are contemplating a long space voyage such as going to Mars and back, figuring out how to make a human more like a hibernating bear would have some advantages.

Image: Øivind Tøien/Institute of Arctic Biology/University of Alaska, Fairbanks