We pick up where we left off last week (“Biomimetics — Where the Action Is“) with more examples of design-based science from around the world.
Gecko astrobot. Get a grip! NASA just launched a space hero to the International Space Station. You could call him Supergecko. Actually, it’s a new material inspired by this superhero among animals, the lizard that can cling to anything. New Scientist says, “In a few years, the exterior of the International Space Station could be crawling with geckos.”
It’s not an alien invasion, or the plot of a low-budget sci-fi movie. The robotic geckos could follow from an experiment NASA launched to the International Space Station on Tuesday aboard an uncrewed Cygnus spacecraft.
The Gecko Gripper devices use tiny artificial hairs that replicate the ones geckos use to climb walls. They are designed to help astronauts to keep track of objects in zero gravity, and enable robots to crawl around a spacecraft to inspect and repair it. [Emphasis added.]
The bots have been tested and are able to grab and manipulate 100-kilogram objects. Instead of using adhesives, geckos adhere to almost anything using atomic van der Waals forces thanks to tiny hairs on their foot pads. “Geckos are nature’s most amazing climbers,” a JPL scientist says. “They go from the floor to the ceiling in 2 seconds.”
Lignin plastic. The woody material in plants, lignin, is finding a new use. In a new alloy with rubber, it’s replacing plastic with a biodegradable, “green” thermoplastic material to replace the petroleum-based plastics used in headgear and Lego pieces. Oak Ridge National Laboratory tells how this new material, using 50 percent renewable content, does not require solvents in its manufacture. It’s a “meltable, moldable, ductile material that is at least ten times tougher than ABS” (the petroleum-based plastic used in many products from car bumpers to kitchen appliances). Another advantage is that it can put the waste from pulp and paper mills to good use. In this case, scientists are not imitating lignin as much as using their own intelligence to combine lignin’s well-designed properties with soft rubber, producing a new material that takes advantage of the plant’s built-in molecular wizardry.
Nature-inspired nanotubes. Thinking about how proteins assemble and fold, scientists at Lawrence Livermore National Laboratory were inspired to copy that “design principle” in the manufacture of nanotubes.
The research is the latest in the effort to build nanostructures that approach the complexity and function of nature’s proteins, but are made of durable materials. In this work, the Berkeley Lab scientists studied a polymer that is a member of the peptoid family. Peptoids are rugged synthetic polymers that mimic peptides, which nature uses to form proteins. They can be tuned at the atomic scale to carry out specific functions.
One can’t fail to notice that man’s best efforts to date fail to “approach the complexity and function of nature’s proteins,” but they think it’s a good start getting just a tube to form. “But building nanostructures is difficult,” they say. “And creating a large quantity of nanostructures with the same trait, such as millions of nanotubes with identical diameters, is even more difficult.” The simplest bacterium has this solution nailed down pat, from coding to manufacture.
Flagellum bots. Inspired by bacteria that swim with their outboard flagellar motors, scientists have created “soft microrobots whose body shapes can be controlled by structured light, and which self-propel by means of travelling-wave body deformations similar to those exhibited by swimming protozoa,” Nature says. Such remote-controlled “microswimmers” could revolutionize medicine by unclogging arteries, fixing immotile sperm, or delivering drugs on demand to specific locations in the body. Microbes, of course, already meet all the design requirements for a microswimmer:
Designing a robust microscopic robotic swimmer that can navigate complex environments and perform useful functions is a key component of the quest. To operate autonomously or on demand, a microswimmer should be able to harvest energy, propel itself through fluid towards its target and respond to external signals. Energy is needed both to overcome the friction of the fluid and to maintain motion for a long time — up to an hour for some biomedical applications.
One team publishing in Nature Materials has succeeded in designing biomimetic “soft microbots” that can swim, driven by structured light. It’s not as fast as a paramecium, but it’s a start at the JV track team. Nature compares a paramecium’s speed with the dolphins we saw in Living Waters swimming in massive pods:
Nature has mastered highly effective means of micrometre-scale propulsion, exemplified by the rotation of helical bacterial flagella, and the wavy beating of the cilia (tiny hair-like structures) that cover Paramecium. This metachronal wave — the sequential movement of thousands of cilia — enables paramecia to swim at astounding speeds, up to ten body lengths per second. (For comparison, a dolphin barely makes two to three body lengths per second when in a hurry.)
Another paper in Nature Communications discusses the subject of microswimmers. First sentence: “Interactions of microswimmers with their fluid environment are exceptionally complex.” Bacteria manage the complexities with ease using their flagella. “This mechanism does not require any active sensing in contrast with fish rheotaxis,” the paper says, speaking probably of salmon fighting their way upstream against the current.
Human epigenetics. This last example is so striking, and so foreboding, as to raise serious questions about the future of biology and of the human race. Scientists at MIT are boasting about a new programming language they invented to program DNA. MIT biological engineers have created “a programming language that allows them to rapidly design complex, DNA-encoded circuits that give new functions to living cells.”
Using this language, anyone can write a program for the function they want, such as detecting and responding to certain environmental conditions. They can then generate a DNA sequence that will achieve it.
“It is literally a programming language for bacteria,” says Christopher Voigt, an MIT professor of biological engineering. “You use a text-based language, just like you’re programming a computer. Then you take that text and you compile it and it turns it into a DNA sequence that you put into the cell, and the circuit runs inside the cell.“
They plan to make the design interface available on the Web. Anyone will be able to create genetic programs — no experience needed.
“You could be completely naive as to how any of it works. That’s what’s really different about this,” Voigt says. “You could be a student in high school and go onto the Web-based server and type out the program you want, and it spits back the DNA sequence.”
On the one hand, this accentuates the case for intelligent design, because it shows that the existing circuits in life represent programs coded for function on a hierarchical scale. On the other hand, can this kind of technology be trusted in the hands of morally challenged humans? What would this technology mean for bioterrorists and rogue nations seeking to employ biological warfare? Could a high school student release a dangerous microbe by mistake?
For now, we’ll defer such discussions to ethicists and theologians. One thing all these examples show, however, is that the imitation of nature depends on design thinking. Think about that.
Image: Gecko Gripper via NASA.