When it comes to robots taking tips from nature to move, there is no shortage of examples from the animal kingdom. Engineers have used dogs, horses, insects and many other animals as inspiration to help their creations walk, fly, swim and crawl.
Now we’re seeing people look even further afield for ideas to get robots to get up and go. Not too long ago, we brought you machines that move because of the swelling and contracting of bacterial spores. Yesterday, researchers from South Korea’s Seoul National University demonstrated another technique that they took from a different kingdom, one that isn’t usually associated with mobility.
Engineer Ho-Young Kim and colleagues looked to the plant world to make a simple legged robot that can walk in a single direction with no power needed besides changing ambient humidity. Their muse? The unassuming pine cone.
Pine cones are the seed-bearing organs of coniferous plants. The cones of many trees include dozens of scales, which can open and close with changing humidity. There are several ideas on why this movement occurs--to aid in pollination or seed dispersal, among other explanations--but the exact function remains a point of debate. Either way, the movement is slow and hasn't been on the radar of roboticists looking to make-fleet-footed machines.
"Plants move slowly -- one cycle of bending and unbending can take an entire day,” Kim said in a release produced in advance of a presentation on their work at the the American Physical Society's 68th Annual Meeting of the Division of Fluid Dynamics. Kim’s team also produced water-strider-inspired robots that can jump from the surface of water earlier this year.
At the heart of their current work is a material with two layers coating it, one made out of nanoscale fibers that swells when humidity increases and another that remains unchanged. This effect is an actuator--a machine muscle--that repeatedly bends and unbends with changing humidity. by attaching little legs to this actuator, they were able to get the robot to move in a direction of their choosing.
They believe their humidity-powered bots could one day find use in medical applications. One area where they think it could be used is in treating skin, which is naturally more humid than surrounding air. "The concept is that by bending, some part of the robot will move away from the skin to encounter dry atmospheric air,” he said. “When it dries, the robot will return to an upright position near the skin. Such a robot could do jobs like disinfecting wounds, removing skin wrinkles, and nourishing skin tissues.”
Top gif: created from video courtesy of Ho-Young Kim.
We’re as enamored as every other nerd with Back to the Future Day lists of unrealized tech the classic movie promised, but we’ve opted instead to bring you gifs of jumping crickets.
These aren’t just any jumping crickets, mind you. These agile and acrobatic athletes are spider crickets, whose beefy hind legs can propel them more than 60 times their body length through the air. Even after a huge jump, the animals can amazingly stick the landing, returning to earth feet-first and then going on their way.
A Johns Hopkins University mechanical engineer and his students have spent the better part of a year studying how the crickets launch and stay stable in air. The hope is that the insects could lead to better designs for robots that need to scramble over rough, uneven terrain during search-and-rescue operations. See a video and learn more below.
By figuring out the mechanics behind their abilities, mechanical engineering professor Rajat Mittal and students think that search-and-rescue robots could use considerably less energy than those built to fly or walk like humans.
To get a better glimpse at what happens when a spider cricket jumps, the researchers trained a slow-motion camera on them that records 400 frames a second. The movements in preparation, execution and mid-air positioning revealed surprisingly nuanced movements.
"These videos have actually been quite eye-opening, because it's only when you slow these critters down that you really start to see the beauty and the intricacy of their movement,” Mittal said. “The analogy that comes to mind is of a ballerina performing a ballet. It's a very beautiful, controlled, intricate motion."
That motion includes body positioning immediately after launch that streamlines the cricket’s posture, minimizing aerodynamic drag and maximizing the distance it can fly. Then, while soaring, the animal uses its limbs and antennae to stabilize flight and prepare for landing. This careful control allows the cricket to land on its feet and be ready to immediately jump again if it needs to escape a predator’s clutches.
"Because they don't have wings, the main things they use during their 'flight' to stabilize their posture is their limbs," said sophomore mechanical engineering student Emily Palmer, who is doing much of the testing. "We're looking at the way the spider crickets move their bodies and move their limbs to stabilize their posture during a jump."
Mittal said such close study had given him and his students a new appreciation for complexity hidden in what appears to be simple actions. "They really are masters of aerodynamics," he said.
Gifs created from Youtube video courtesy of Johns Hopkins.
Geckos, the lizards whose amazing toes let them adhere to almost any surface, may just be the poster animals for innovation in 2015. Everywhere you look, the little creatures are inspiring engineers and materials scientists to push the envelope on new adhesives and coatings.
Earlier this year, Stanford showed off a robot that could pull 100 times its own weight using gecko physics. NASA has also announced it will use robots with feet like the lizard’s to crawl around the outside of the International Space Station for inspection and repair. There’s even a system being developed to let people strap on foot and hand pads to be like Spider-Man.
Now a Carnegie Mellon University spinoff company called nanoGriptech has announced that it is launching the first commercially available gecko-inspired adhesive into the market. The company says their dry coating can be used in manufacturing, medical settings, in safety and defense applications and even for better soccer goalkeeper’s gloves.
(nanoGriptech’s soon-to-be commercially available gecko-inspired adhesive coatings have been used to make robot fingertips that can turn book pages and robots that can climb vertical and inverted smooth surfaces. Gifs created from Youtube video courtesy of Metin Sitti.)
The Pittsburgh-based company calls their first offering Setex, an adhesive material that uses no glue, leaves no residue and can be reused without losing its gripping strength.
"Much like Velcro or Kevlar, we believe Setex will disrupt markets because of its many commercial applications," said Roi Ben Itzhak, nanoGriptech CFO and vice president of business development, in a university statement. "There are other gecko-inspired materials in labs around the world, but, unlike Setex, they all have weak peel strengths and are prohibitively expensive to manufacture."
Setex and its competitors all rely upon the same physics to mimic the gecko’s nearly magical clinging abilities. Reversible adhesive power comes from tiny structures on the coating that hold onto surfaces with van der Waals force, a phenomenon where polarized molecules making up the minute structures cause an attractive force to the surface’s molecules.
Setex accomplishes this by building microscopic polyurethane posts with mushroom-like flat tips. Each fiber exerts an attractive force to a surface it comes in contact with. The company says several square inches of the adhesive can support hundreds of pounds of weight hanging from it.
(A closeup view of the Setex fibers responsible for gecko-inspired adhesion. Gif created from video courtesy of nanoGriptech.)
Along with sticking objects together, the coating can be used to help manufacturing robots performing pick-and-place operations, create better clothing fasteners and surgical tool grips or to give prosthetic hands a gripping upgrade.
(nanoGriptech’s dry reversible adhesive is used on a manufacturing robot’s pick-and-place operations for a fragile item. Gif created from video courtesy of the company.)
nanoGriptech just received a big endorsement of its work by Breakout Labs, which invests in early-stage companies doing potentially transformative work in fields from biotech to clean energy. The organization says it will provide funding to the startup and make it one of its portfolio companies.
“We envision a future filled with no-leak biohazard enclosures, ergonomic and inexpensive car seats, extremely durable aerospace adhesives, comfortable prosthetic liners, high performance athletic wear, and widely available nanotechnology-enabled products manufactured less expensively — all thanks to the grippy little gecko,” said Ben-Itzhak as part of the Breakout Labs announcement.
A project harnessing squid genetics to develop a plastic that reattaches after it has been cut in two could be a significant advance for self-healing materials, according to a study published this month.
The squid-based polymer, shown in the gifs above, displays mechanical strength that can be recovered after the material is cut. All it takes is a drop of water, low pressure and some heat, and two pieces fuse back into one. The multinational team behind the research says their material could potentially make self-healing fiber-optic cables and medical implants.
“What’s unique about this plastic is the ability to stick itself back together with a drop of water,” said Penn State engineer Melik Demirel. “There are other materials that are self-healing, but not with water.” Learn more and see images below.
Their inspiration came from proteins in the ring teeth of squid. They found that hard and stiff polymers with the material can plasticize and self-heal at around body temperature when water is added. Their source was the European common squid, which had been found in previous studies to have at least seven proteins that temporarily turns normally glasslike ring teeth rubbery to repair cracks.
(Squid ring teeth proteins can be mixed across species to engineer the required properties. Courtesy of Demirel Lab/Penn State.)
“Self-healing materials are able to partially or completely heal damage inflicted on them, in particular by repairing cracks,” they write in the journal Nature Scientific Reports. “Stiff materials that self-heal in wet environment would greatly benefit biomedical applications, in particular by extending the lifetime of implants, but most self-healing polymeric chemistries are not suitable for aqueous environments.”
But these proteins can’t be harvested in large enough quantities to make them potentially useful at industrial scales. So the team did the next best thing--they got the blueprints for the proteins by probing the squid’s DNA with next-generation sequencing. Then they used genetic engineering to reprogram E. coli bacteria and make it pump out the proteins in much larger quantities.
Once purified, the material can be cast or molded into any shape.
“If one of the fiber-optic cables under the ocean breaks, the only way to fix it is to replace it,” Demirel said. “With this material, it would be possible to heal the cable and go on with operation, saving time and money. Maybe someday we could apply this approach to healing of wounds or other applications.”
All gifs created from Youtube video courtesy of Penn State.
A Seahorse Tail Could Inspire Better Robots, Surgical Tools
by Michael Keller
An advance in understanding why the seahorse’s tail is made of square plates could inform the next generation of robotics and armor. In an engineering study that looked at the mechanics of how the fish’s tail works, researchers found the structure’s shape is optimized to resist crushing and to grasp while bending and twisting.
An international team modeled the stresses and strains of the tail bones with a computer and 3-D printed prototypes to subject them to engineering tests. They believe that the superior resistance to compression is an adaptation to protect the fragile spinal cord that runs the length of the tail.
One of their primary questions was why evolution would select for square prisms in the seahorse skeleton when other animals that do similar things with their tails have developed cylindrical ones. Learn more and see images below.
(Computer animation of moving vertebrae and surrounding plates in a seahorse’s tail, showing the gliding joint between the consecutive plates. Gif created from video courtesy of Dominique Adriaens/UGent.)
(Video-recording of a Hippocampus erectus specimen (Lined seahorse) swimming along and eventually grasping onto a dowel. Gif created from video courtesy of Dominique Adriaens/UGent.)
"Almost all animal tails have circular or oval cross-sections--but not the seahorse's. We wondered why," said Clemson University mechanical engineer Michael Porter, who led the study. "We found that the squared-shaped tails are better when both grasping and armor are needed."
The work is a continuation of Porter’s years of investigating the seahorse tail, which is composed of 36 square prisms, each built of four L-shaped plates. Using the models and prototypes, they found the square design allowed the seahorse tail to realign itself after being twisted and bent. With greater surface area and dexterity, the tail also lets the animal hold steady in currents by firmly grasping slick seaweeds or uneven coral.
Most importantly, crushing a cylindrical model and a square one showed that the square prisms resisted deformation more than the prototype with a round cross section. This resilience is attributable to ingenious sliding joints built into the skeletal plates that let them glide past each other. The joints allow for just one degree of freedom when they start getting crushed. Circular plates in the cylindrical model, meanwhile, both slide past each other and rotate, making them able to absorb less energy before failure.
"We found that this square architecture provides adequate dexterity and a tough resistance to predators, but also that it tends to snap naturally back into place once it's been twisted and deformed," said Oregon State University mechanical engineer Ross Hatton, who coauthored the study that appeared last week in the journal Science.
(Pictures of the two 3D-printed prototypes crushed by a rubber mallet. Notice how the overlapping joints allow the plates to slide past each other and absorb energy on impact. Photo courtesy of Michael M Porter.)
In a commentary that appeared in the same journal, Wake Forest University biologist Miriam A. Ashley-Ross, who was not involved in the research, wrote: “Porter et al. suggest that a square tail provides superior resistance against compressive injury (i.e., a bite from a predator), and that the improved armor function may have been the driving force in its shape evolution…As they predicted, the square version demonstrated greater resistance to compression (higher forces required to make the “tail” deform by a given amount), and tolerated more actual compression, in both one and two dimensions, without damage.”
The research team said the insights they’ve gleaned from the seahorse tail could have a range of robotics uses where strong, agile and energy-efficient design is needed. Among the applications they believe the seahorse tail engineering know-how could work are search and rescue robots or tools meant to navigate through rubble, surgical instruments that need to contort through the body or for industrial robotics.
"Human engineers tend to build things that are stiff so they can be controlled easily," said Hatton. "But nature makes things just strong enough not to break, and then flexible enough to do a wide range of tasks. That's why we can learn a lot from animals that will inspire the next generations of robotics."
If you were a field mouse minding your own business and foraging for some food in the forest, the last creature you’d want to spot you would be an owl. The reason is simple--even as the bird of prey swooped down with talons open, you’d never hear it coming.
Owls have an impressive superpower in silent flight, made possible by specialized wings and feathers that disperse the sound of air rushing past them. Now an international research team says they have taken a tip from owls that could eventually lead to turbine blades and jet aircraft that produce significantly less noise.
“No other bird has this sort of intricate wing structure,” said University of Cambridge applied mathematician Nigel Peake. “Much of the noise caused by a wing – whether it’s attached to a bird, a plane or a fan – originates at the trailing edge where the air passing over the wing surface is turbulent. The structure of an owl’s wing serves to reduce noise by smoothing the passage of air as it passes over the wing – scattering the sound so their prey can’t hear them coming.” Learn more below.
The problem they are trying to solve is that fact that any type of airfoil—whether it’s a wind turbine blade, an aircraft wing or fan blades inside a jet engine or computer cooling system—create turbulence that rolls off their trailing edge as they move through air. That turbulence causes sound waves that bystanders hear as noise.
They made a prototype coating from 3-D printed plastic that included raised ribs and tested it on an airfoil in a wind tunnel. Placing it just upstream of the foil’s trailing edge, it altered the turbulence coming off the foil and reduced noise by 10 decibels.
Virginia Tech aerospace and ocean engineer William Devenport, who participated in the work, said the design likely works by chopping up turbulent air flow right before it passes over the foil’s trailing edge. This deconstruction might make the turbulent air unable to produce sound waves with the same power. “We think this is a whole new way of looking at noise control,” Devenport said.
They also believe that there’s room to optimize the coating’s design, perhaps improving its sound-dampening effect. The aerodynamic impact of the coating on the airfoil’s “appears minimal,” the group concluded in a paper presented last month during an American Institute of Aeronautics and Astronautics conference.
If that type of reduction could be maintained in the field, the noise level just 330 feet from an operating commercial power-generating wind turbine would be roughly the equivalent of a refrigerator’s hum. Or, with less noise being generated, a wind turbine could be operated at higher rotational speed to produce more power—up to an additional several megawatts for the average wind farm—with less noise.
See Dr. Sahin’s Wondrous Spore-Driven Evaporation Engine
It sounds like a steampunk fantasy, but it is, in fact, a real thing.
Columbia University bioengineers have built a number of working engines powered by water evaporation and contracting and expanding bacterial spores. The machines represent the first time the humidity that naturally rises from evaporating water has been used as a fuel source.
Biophysicist Ozgur Sahin and his colleagues built evaporation-driven devices that enabled a miniature car to move, a mill to spin, weight to be lifted and an oscillatory engine to power LEDs.
The work is actually a continuation of research we reported on in 2014 to generate electricity and make robot muscles from the force of hydrating and dehydrating microbial spores. But where that study showed only rudimentary lengths of polymer film coated with the spores flexing when in contact with water vapor, the group has now created working machinery using the phenomenon. Learn more and see a video below.
“Evaporation is a ubiquitous phenomenon in the natural environment and a dominant form of energy transfer in the Earth’s climate,” Sahin and coauthors write in a paper on their work published today in the journal Nature Communications. “Engineered systems rarely, if ever, use evaporation as a source of energy, despite myriad examples of such adaptations in the biological world.”
Dormant spores of the bacterium Bacillus subtilis are responsible for the engines’ power generation. As nearby water evaporates, the vapor is absorbed by the spores and they expand. That movement exerts a surprising amount of force that the researchers harness to make power. In their experiments, the group found vertical strips of spore-coated polymer film could lift 50 times their weight, rivaling the work mammalian muscle fiber can do pound for pound.
“Demonstrations made here with the evaporation-driven car and the powering of LEDs highlight the so-far overlooked capability of water in the environment to supply useful levels of power,” the authors conclude. “Due to the ubiquity of evaporation in nature and the low cost of materials involved (plastic tapes, hygroscopic materials), the engines presented here may find applications as energy sources for a wide range of off-the-grid systems that function in the environment.”
While these toy-like demonstrations may appear to be nothing more than an interesting diversion, scientists not associated with the work say they are a powerful proof of concept for a new power production strategy.
“These are fun demonstrations, but they prove the principle,” Peter Fratzl, a materials scientist at Germany’s Max Planck Institute of Colloids and Interfaces who was not involved with the work, told Science Magazine. “It makes sense to use these gradients [in humidity], because they’re everywhere and they’re free.”
All gifs created from videos courtesy of Chen et al./Nature Communications.
Strong Glass Sea Sponge Hairs Could Inspire Better Construction Materials
The image above on the left shows the cross section of a nearly pure glass cable. While only 50 microns across, it is organized in a complex structural arrangement that includes a solid silica glass core surrounded by up to 50 concentric cylinders of glass that are each separated by a thin layer of organic material. As you move away from the core, each cylinder is thinner than the one before, as shown in the visualization to the right. This design gives the cable unique strength not normally associated with glass.
It would make sense to hear that the complex engineering behind this cable came out of a well-funded industrial or government lab. Perhaps groups of the lines bundled together would make up the data-transmitting undersea telecommunications cables that must endure crushing pressure. Well, it turns out that the cable does sit on the seafloor--it is grown by a species of marine sponge that uses an array of the cable-like hairs, called spicules, to anchor the animal to the ground.
“It was not at all clear to me what this pattern was for, but it looked like a figure from a math book,” Kesari said. “It had such mathematical regularity to it that I thought it had to be for something useful and important to the animal.”
(The Venus’ flower basket sea sponge uses extraordinarily strong spicules — strands of nested glass columns--to anchor itself against flowing currents. Courtesy Brown University.)
Kesari and colleagues’ work understanding the design was published April 6 in a paper in the Proceedings of the National Academy of Sciences. It details how evolution worked to perfect its geometric form and function because sponges that can’t stay firmly anchored in currents are unable to filter out food from the water they need to survive. Such an important survival structure would experience significant pressure from natural selection to come to a design that works best.
“If it can’t anchor, it can’t survive,” Kesari said. “So we thought this internal structure must be contributing to these spicules being a better anchor.”
While understanding the biology and natural engineering of the sponge’s spicules is interesting in its own right, the team is also interested in how the hairs’ design principles can be used to improve human-made products. They are interested in applying the idea behind increasingly thinner concentric cylinders that improve structural strength to things like load-bearing structures in buildings.
“In the engineered world, you see all kinds of instances where the external geometry of a structure is modified to enhance its specific strength — I-beams are one example,” said graduate student Michael Monn, who worked on the mathematical model that uncovered the design’s strength advantage. “But you don’t see a huge effort focused toward the internal mechanical design of these structures.”
(Venus' Flower Basket [Euplectella aspergillum] growing on the seafloor. Image courtesy NOAA/Wikipedia.)
Top Image: A mathematical model, right, predicts that the thickness of nested glass cylinders should decrease from the core to the exterior to optimize strength. Studies of hundreds of spicules, left, showed that was exactly the case in nature. Image courtesy of Brown University.
