GUEST POST: Reverse Engineering the Gecko and Other Advancements from the World of R&D
Guest post by Doug Hornig of Casey Research
Technology advances so fast that it's impossible - even for people who dedicate their lives to it - to keep up with everything that's going on, let alone the average investor with a whole other life to live doing so. With this information gap in mind, we'd like to bring you some of the more interesting research and development stories we've come across recently.
There are any number of ways that scientists come up with their ideas for new products. But one of the most time-honored is to go back to nature. If something has worked out there in the natural world, maybe it can be replicated in the lab.
Beyond copying the shape of wings or legs, few phenomena in nature happen above the microscopic scale. Until recently, that made it quite difficult for us to reproduce many of the miniature miracles that nature uses every day. But with advances in nano-scale manufacturing, researchers are once again turning to nature, and to their imaginations, to inspire a new generation of materials.
That's what some German researchers were thinking as they set out to, in essence, reverse engineer the gecko.
Fifteen Minutes Can Save You...
Didn't you ever wonder how it is that this lowly creature can scamper up walls and across ceilings without falling? Turns out, it's both simple and complex.
The simple part is that the gecko has thousands of tiny hairs, called "setae," covering its feet and legs. The hairs are not only numerous, they're coupled with flattened tips that can splay out to maximize contact on even rough surface areas. It's these that enable the animal to maintain adhesion to whatever it's traversing.
The more complicated part is why this works, especially when the gecko is upside down. In a pull/push contest between gravity and some miniscule setae, no matter how many of them there are, intuition suggests that the former should prevail; yet direct observation proves that it does not. Furthermore, if the gecko's feet are sticky enough to overcome gravity, how does it ever get unstuck?
It has to do with the van der Waals force, named for the Dutch theoretical physicist of the late 19th-early 20th century, Johannes Diderik van der Waals. The force - actually a collection of several forces - is defined in the International Union of Pure and Applied Chemistry Gold Book as:
The attractive or repulsive forces between molecular entities (or between groups within the same molecular entity) other than those due to bond formation or to the electrostatic interaction of ions or of ionic groups with one another or with neutral molecules. The term includes: dipole-dipole, dipole-induced dipole and London (instantaneous dipole-induced dipole) forces. The term is sometimes used loosely for the totality of nonspecific attractive or repulsive intermolecular forces.
In other words, they kinda don't know exactly what's going on there, but we can see the effects. The attractive power of the van der Waals force that exists between gecko feet and the ceiling exceeds that of any repulsive force. It also exceeds the gravitational attraction of the Earth below.
(Gravity, though we tend to think of it as strong, is really quite weak. Consider that a body as massive as the Earth is incapable of keeping anything with legs or wings constantly plastered to it. We can't pole vault into space, of course, but animals can jump pretty high and soar even higher, and we can launch small projectiles free of the planet.)
Gravity is not powerful enough to pin the gecko to just one spot. Thus, the creature can walk just fine above our heads, up and down walls... pretty much wherever it wants.
So, now that we get the overall picture, why can't we do it, too? A lot of people want to. The quest for the so-called "Spiderman" suit has consumed a ton of research dollars - especially within the military, where its obvious potential usefulness has made it one of modern warfare's holy grails.
We don't have one yet. Physicists at the Polytechnic University of Turin came up with a design using carbon nanotubes back in 2007, but a working model has proven impractical. However, we're inching closer. Check out this fellow:
Image: Wahj via Flickr
He's Achim Oesert of the University of Kiel in Germany, and he's hanging from a 20 x 20 cm square of silicone tape created by his research team.
The bio-inspired tape's construction features hairs similar to setae, and it sticks to a surface via the van der Waals force. It is not only strong enough to support a human, as you can see, but it can work underwater and leaves no sticky residue. Best of all, it can also be attached and detached thousands of times without losing its adhesive properties.
It's the triumph of the gecko.
Not only are we looking at a whole new generation of adhesive products, but we're closing in on the day when we'll be able to slither up walls without the CGI assist that Spiderman needs.
It Hit Me Like an Ounce of Bricks
At the opposite end of the spectrum are researchers who don't take their inspiration from nature but are creating things entirely new to the universe from scratch, using building blocks from nanotechnology. In this arena, a lot of extraordinary and exciting things are happening.
One of the latest developments is the micro-lattice.
Image: Dan Little, HRL Laboratories, LLC
What you see above is a structure that looks substantial but really isn't. It's a mesh so ethereal that it doesn't disturb the dandelion fluff. It's being billed as the world's lightest construction material, and it almost certainly is. At just 0.9 milligrams per cubic centimeter, it's 99.99% air, 100 times lighter than Styrofoam, and less than one-thousandth the density of water. When dropped from shoulder height, the micro-lattice floats like a feather, taking about 10 seconds to reach the ground.
Yet it is metal, fashioned from interconnected, hollow nickel-phosphorous tubes with a wall thickness of 100 nanometers - 1,000 times thinner than a human hair. The tubes are angled and connect at nodes to form repeating, three-dimensional, asterisk-like cells. Think the Eiffel Tower - which is also very light and weight-efficient thanks to its hierarchical lattice design - but at microscopic scale.
The super-lightweight lattice is the result of research carried out by a team from UC Irvine, HRL Laboratories, and the California Institute of Technology; their report was published in the November 18 issue of Science.
In addition to being ultralight, it's also strong and better yet, energy absorbent. Spongy. It can suffer compression up to 50% of its height and spring back into shape, as you can see in this video.
For now, the applications being considered include things like soundproofing and impact protection. But imagine a car with a body made of material inspired by this stuff - so light it'd probably get a hundred miles to the gallon. Plus, a fender-bender would be self-repairing; no trip to the body shop needed.
We can hardly wait.
3D Printing Meets Robotics
Going back to an inspiration from nature and two of our favorite areas of technology - robotics and 3D printing - we'd like to share with you the jumping spiderbot:
This little guy is the brainchild of researchers at Germany's Fraunhofer Institute for Manufacturing Engineering and Automation.
Borrowing from nature, the Fraunhofer team wanted to create a robot with the agility and stability of real spiders when getting around, along with special joints that allow it to jump. Four of its eight-inch legs are on the ground at any one time, while the remaining four can turn and ready themselves for the next step. Diagonally opposed members can also move simultaneously. Bending the front pairs of legs pulls the spiderbot's body along, while stretching the rear legs pushes it. Finally, the spiderbot's legs and body are fitted with pneumatically operated, elastic drive bellows that bend and extend its legs with the force required for jumping.
The control unit, valves, and compressor that drive the beast are built into the robot's body, which could also be fitted with various measuring devices and sensors should the spider ever be dispatched to a job out in the real world.
For construction of the spiderbot's parts, the Fraunhofer team eschewed more conventional engineering technologies and turned instead to selective laser sintering (SLS), which fuses a powdered polyamide material by scanning cross-sections of the desired object on the surface of the powder bed. This production method offered the advantage of allowing complex geometries and inner structures to be constructed, while ensuring that the result will be lightweight and extremely cheap to produce. Individual parts can be quickly remade and swapped out if they fail, without having to keep a stamping machine on standby.
The spiderbot is merely a prototype at the moment, but subsequent versions could have a bright future exploring environments that are too hazardous or difficult for human access, such as cave-ins or nuclear accident sites.
[The plethora of exciting developments in technology are changing the world as we know it, and nowhere is this more true than in biotechnology and health care.]
Doug Hornig is senior editor of the Casey Daily Dispatch .
Labels: Casey Research