Biomimetics: Design Science Is Flourishing
Some research centers appear to be on the verge of a golden age – the age of biomimetics (the imitation of biological design). Products that will change our lives are springing from designs inspired by studying how plants, animals and cells have solved real-world problems. Although some of the research mentions evolution, the real power behind the research and development is the word design. Here are just a few recent examples.
- Make a muscle: Scientists at the University of British Columbia are taking inspiration from muscle proteins. They want to design materials that mimic their mechanical properties, “which are a unique combination of strength, extensibility and resilience,” they said in their paper in Nature.1 The chief molecule responsible for these desirable properties is a giant protein aptly named titin. It acts like a “complex molecular spring” thanks to “a series of individually folded immunoglobulin-like domains as well as largely unstructured unique sequences.”
The scientists have now succeeded in recasting solid biomaterials by making “artificial elastomeric proteins that mimic the molecular architecture of titin” that “behave as rubber-like materials showing high resilience at low strain and as shock-absorber-like materials at high strain by effectively dissipating energy.” They call it a new “muscle-mimetic biomaterial.” Even though it is a passive substance, they can tweak it: “The mechanical properties of these biomaterials can be fine-tuned by adjusting the composition of the elastomeric proteins, providing the opportunity to develop biomaterials that are mimetic of different types of muscles,” they said.
Wow; will this be the new flubber? “We anticipate that these biomaterials will find applications in tissue engineering as scaffold and matrix for artificial muscles.” Watch for the biceps on upcoming robots. Elliot L. Chaikof commented on this paper in the same issue of Nature,2. He said that biological materials are attractive because they allow for dissipation of energy and damping vibrations that prevent structural failure. “The elasticity and energy-recovery properties of such structural proteins are therefore fine-tuned for their biological roles, and are crucial determinants of the normal physiological responses of a broad range of tissues, including those that comprise the cardiovascular and musculoskeletal systems.” The problem with synthetic materials in biomedical devices (microvalves, microactuators, etc.) is that “they cannot facilitate tissue repair, remodelling or regeneration, and they often provoke maladaptive host responses at tissue�material interfaces.” Creating parts out of protein is therefore a worthy goal. Chaikof reminds the reader that we are merely at the frontier:
Lv and colleagues’ material is certainly impressive, but is it a true muscle mimic? Muscles are complex molecular machines, in which several components are assembled into well-ordered structures capable of converting a stimulus into motion. Titin is a major constituent of muscle, but a titin mimic alone does not reproduce all the properties of muscle – such as its tensile strength, or force-generating and force-sensing abilities. In the absence of a self-repair mechanism, protein-based materials are also inherently susceptible to biological degradative processes after implantation, which could release ‘foreign’ protein fragments into the host. For biomedical applications, such materials therefore need to be carefully assessed to ensure that no fragments cause adverse immune reactions. Future work will undoubtedly address these issues, leading to creative designs and fabrication techniques for assembling artificial muscle elements that reproducibly and repeatedly respond on command, perform work, and function well after surgical implantation.
Flubber basketball players may have to wait a while longer. This job is harder than it looks. Science Daily reproduced a press release from UBC about the progress so far; see also PhysOrg’s headline, “Designed biomaterials mimicking biology: Potential scaffold for muscle regeneration.”
- Moths are the prototype: A perfectly non-reflecting display would be really cool for your eyeglasses or camera lenses. “Moths are the prototype” for a new nanocoating being developed at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany. Science Daily explained that moths have to avoid predators while flying about at night. While other insects’ multi-faceted eyes shimmer under light, “the moth’s eyes are perfectly non-reflecting.” That’s because “Tiny protuberances smaller than the wavelength of light form a periodic structure on the surface. This nanostructure creates a gentle transition between the refractive indices of the air and the cornea. As a result, the reflection of light is reduced and the moth remains undetected.”
That trick is being imitated in a new process that applies the anti-reflective surface structure during manufacture of the component, without having to add a second coating process. This not only saves money but increases durability. The materials the Fraunhofer team is making are strong, scratch-proof and easy to clean. Imagine soon having cell phone displays, dashboard display covers, eyeglasses, and any other transparent surface that have all these desirable properties – thanks to the lowly moth.
- Purple is the new green: Purple bacteria, that live in the bottom of lakes and in coral reefs, are among the very best at harvesting energy from sunlight. According to an article in Science Daily, “Its natural design seems the best structural solution for harvesting solar energy.” That’s why “Neil Johnson, a physicist and head of the inter-disciplinary research group in complexity in the College of Arts and Sciences at the University of Miami, thinks its cellular arrangement could be adapted for use in solar panels and other energy conversion devices to offer a more efficient way to garner energy from the sun.”
Johnson said (without first-hand observation) that these bacteria have been around for billions of years, and “you would think they are really simple organisms and that everything is understood about them.” But it was recently discovered that they can “adopt different cell designs depending on light intensity.” That realization “could help direct design of future photoelectric devices.”
Purple bacteria have some tricks up their sleeves. They use a non-intuitive technique to squeeze more energy out of available light. To optimize, they can’t stay wide open all the time; they have to adjust the input to the ability to process the energy – which they do. They hit a balance: “purple bacteria create a design that balances the need to maximize the number of photons trapped and converted to chemical energy, and the need to protect the cell from an oversupply of energy that could damage it,” Johnson explained.
At this point, the scientists are just trying to understand how the bacteria do it. “Currently, the researchers are using their mathematical model and the help of supercomputers, to try to find a photosynthetic design even better than the one they found in purple bacteria, although outsmarting nature is proving to be a difficult task.” Maybe its just too hard. So why not save energy, and harness the bacteria themselves? “Because these bacteria grow and repair themselves, the researchers hope this discovery can contribute to the work of scientists attempting to coat electronic devices with especially [sic] adapted photosynthetic bacteria, whose energy output could become part of the conventional electrical circuit, and guide the development of solar panels that can adapt to different light intensities.”
- Between the fern and the deep blue sea: “Tiny Hydrophobic Water Ferns Could Help Ships Economize on Fuel,” Science Daily announced. How is that? “The hairs on the surface of water ferns could allow ships to have a 10 percent decrease in fuel consumption,” the article explained. “The plant has the rare ability to put on a gauzy skirt of air under water.” That translates into reduced friction, which translates into fuel savings.
The tiny water fern Salvinia molesta is so hydrophobic, it never gets wet – even under water. You can pull it out of the water and the water just drips right off, leaving it completely dry, even after it has been underwater for weeks. Imagine having swimsuits and scuba equipment like that. Previous attempts to create superhydrophobic materials have not been stable enough to last. Scientists have known about the fine hydrophobic hairs on the water fern, but they recently discovered that the tips of the hairs are hydrophilic – they attract water. Strange as that seems, it sets up a water layer that holds the air layer close to the plant. One colleague was excited by this: “After the solving of the self-cleansing of the lotus leaf twenty years ago, the discovery of the salvinia effect is one of the most important new discoveries in bionics.”
Half the energy of moving a cargo ship through the water is caused by friction at the hull-water interface. A ten percent saving on fuel costs by coating the hull with a salvinia-effect material could have an enormous impact. “Surfaces modelled on the water fern could revolutionise shipbuilding,” the article concluded.
- Synchronized swimming: The dancing of a school of fish like a single organism moving gracefully through the water is a visual treat. “Nature shows and Caribbean vacation commercials often depict a school of fish moving as a single entity to avoid obstacles and elude prey,” PhysOrg agreed, adding, “Engineers hope to give unmanned mini-submarines, mini-helicopters and other autonomous vehicles the same coordinated movement.” To do that, they first need to understand how the fish do it.
“Fish signal one another via visual cues and hydrodynamics (the movement of water),” the article explains, describing research at the University of Maryland. “A line of tiny hair cells down each side of a fish helps them to sense the flow of the water around them.” A short video shows how the researchers are making their first clumsy attempts to get yard-long robotic submarines in a tank to read each other’s visual cues, using cameras, to steer. Another researcher is working on the hair cell mimics. All the while, they are monitoring a school of live fish called giant danios to learn from their coordinated movements. They’ve learned that one fish getting startled can set off a “wave of agitation” that propagates from neighbor to neighbors. Another video shows computer models built on the observations. “We’re developing modern engineering tools to quantitatively study this phenomenon,” the lead researcher said, an aerospace engineering professor with the design-friendly name Paley. “We’re taking methods you learn as an engineering student and applying them to study biology.” Next stop: synchronized aerial vehicles exploring the eyes of hurricanes, schools of unmanned submarines gathering data in the deep ocean, maybe even synchronized spacecraft.
- Autonomous roach robots: Artificial robots, including drones, unmanned subs, Mars rovers and spacecraft, have to be driven by humans. Often it takes too long for signals to reach the moving parts to avert danger, and the robot gets stuck. Roy Ritzmann at Case Western Reserve University is envious of roaches. They respond to obstacles so nimbly, he decided to wire their neurons to see how fast their brains command their legs. PhysOrg describes his work in “If only a robot could be more like a cockroach.”
The way we design robots now is too clumsy for the kind of work we need them to do – to go into the World Trade Center looking for victims, or other rescue situations. “So, to make a robot that can turn, back up, climb over or burrow under and obstacle without the guidance of a far off rescue worker using computer controls, what could be better than mimicking an insect’s comparatively simple brain?” Ritzmann thought. “Easier said than done,” found Ritzmann and his assistant Allan Pollack. If you can imagine doing brain surgery on the head of a pin, that’s about what it took to wire a roach brain to study its neuron firing patterns when it walks. They found that steps occur about 450 milliseconds after a neuron fires. The cockroach is controlling the speed of its legs with its brain. If we can ever get our robots to do that, we’ll really have something – especially if we can get them that small, and able to climb walls and reproduce themselves. On second thought… restaurants, watch out.
Overlapping with biomimetics is genetic engineering. Once living designs are understood, they can be tweaked in ways humans desire. New Scientist reported on ways that plant leaf shape, stomata density and photosynthesis rate might be adjusted genetically. Linda Geddes began the article on “Designing Leaves” by saying, “From blades of grass to the cup-like fly-catcher of the pitcher plant, the diversity of leaf shapes, sizes and structures is stunning. It is also incredibly useful, allowing plants to live nearly everywhere on Earth, from the deserts of the US Midwest to the lush shores of the Amazon. Now the precise molecular switches that control the process are being unpicked.” Once we understand how leaves grow and prosper, the question becomes, “what does an optimal leaf look like and can we design one?” If so, we may be on the verge of the next green revolution – producing crops with dramatically increased yields, making food plants more resilient to heat and drought, and taking the guesswork out of selective breeding.
1. Lv, Dudek, Cao, Balamurali, Gosline and Li, “Designed biomaterials to mimic the mechanical properties of muscles,” Nature 465, 69�73 06 May 2010; doi:10.1038/nature09024.
2. Elliot L. Chaikof, “Materials science: Muscle mimic,” Nature 465, 44�45 06 May 2010; doi:10.1038/465044a.
All together now: “These articles said nothing about evolution.” This is all design, design, design. We are marveling at the design and complexity of living solutions to real engineering problems, and trying to imitate them. If imitation is the sincerest form of flattery, who are we trying to honor? For any Darwin Party maniacs reading this, worried that the r-word is coming, notice that all this research, though completely compatible with an intelligent-design approach to science, had nothing to do with religion. It shows that science can approach nature with regard to intelligent design without focusing on the identity of the designer, Designer, or God.
In the ID Revolution, everyone can join in and get on board without starting a religious war, because the focus is on design detection and design imitation. Questions about the Designer are, of course, very interesting and important, and very compatible with all this research, but those discussions can be left in the hands of capable theologians and philosophers. Individual scientists do not have to state their affiliations in their papers. None of these did; and none of these felt compelled to tell Darwinian tales, either. If journals will just loosen the reins, and let scientists like these talk about design, even intelligent design, without getting whipped for using the phrase, all they would be doing is validating what is already taking place.
Simultaneously, journals need to relax the requirement for allegiance to Darwinism. Just-so stories are becoming so 1940s. It’s getting harder and harder for observational scientists to maintain belief that blind chance could produce optimized computers (see next entry), synchronized robots, perfectly non-reflecting surfaces, and so many other marvels. Isn’t it time to jettison the bad habit of force-fitting Information-Age discoveries into a worn-out Victorian mindset? Intelligent design science is not so much about controversial additions to science. As you can see in the articles above, design thinking is already being put to great use. It’s more about some blessed subtractions.