Learning from Nature II

Stephen DeAngelis

January 5, 2010

I first discussed how designers are drawing from the world around them for inspiration in a 2007 post entitled Turning to Nature to Save Energy. In January 2009, I wrote another post on the subject entitled Learning from Nature. In the latter post, I discussed how scientists and designers are turning more frequently to the natural world to see how evolution has solved some of life’s difficult challenges for other species. Biomimicry, as the practice is called, continues to make headlines [“Scientists raid mother nature’s cupboard,” by Jonathan Soble, Financial Times, 10 December 2009]. Soble reports:

“Japan’s industrial designers are turning to plants and animals for ideas on everything from tackling traffic jams to conserving household energy. Their inventions could help the country meet its ambitious targets for reducing greenhouse gas emissions – a daunting task in what is already the world’s most energy-efficient industrial economy. Yukio Hatoyama, prime minister since September, has pledged to cut emissions by a quarter from 1990 levels by the end of the next decade, and is promising billions of yen in support for ecofriendly innovations. Japan’s most prominent example of high-tech borrowing from nature, a technique sometimes called ‘biomimicry’, is found on the Shinkansen – the high-speed bullet trains whose noses now look less like bullets than the swooping bills of birds. The style is deliberate. Engineers at JR West, a railway, were looking to eliminate the sonic booms that the trains created when they barreled through tunnels, violently compressing the air inside as they went. They found a solution in the kingfisher, a marine bird whose long, flattish bill produces very little splash when the animal dives into the water for prey. Trains built on the Kingfisher design slice through air even in narrow spaces. In addition to quieting the ride, their improved aerodynamics help them travel 10 per cent faster on 15 per cent less power.”

Mother Nature has become quite adept at helping creatures become energy efficient. To survive in a world where creatures spend most of their time either searching for food or trying to conserve energy, becoming energy efficient is imperative. Soble continues:

“Transport engineers have particularly strong reasons to copy nature, with its panoply of flying, burrowing and wall-climbing creatures. Nissan Motor, Japan’s third-largest car manufacturer, is studying how fish manage to swim in quick-darting, tightly grouped schools without smacking into one another. It has created packs of tiny robots that mimic fish behavior, and hopes eventually to incorporate the algorithms that control them into its cars, where they could help manage traffic flow and prevent crashes.”

Not all energy efficient devices have to have moving parts. Soble discusses ceramic tiles being created in Japan that drew inspiration from nature. He continues:

“Another company that is embracing biomimicry is Inax, a manufacturer of bathroom fixtures whose products include Japan’s famously high-tech toilets. Inax has recently begun selling ceramic floor tiles that have been compressed in super-heated water, a process similar to that which produces some natural stones. Microscopic air pockets let the tiles ‘breathe’ and keep rooms cool in the summer and warm in the winter. Inax says its tests show that electricity use falls by an average of a quarter in homes that have the tiles installed, due to reduced need for heaters and air conditioners. … Emile H Ishida, a former Inax engineer who developed the tiles … [and] now a professor at Tohoku University’s Graduate School of Environmental Studies, … [has developed] another novel tile … [that] is covered in tiny protein-lined ridges that mimic the slick surface of a snail’s shell. A splash of tap-water removes virtually any dirt or stain – a property that he demonstrates by mucking up tiles with oil and soot, then rinsing them clean like a salesman in a television advert. Installing such tiles in bathrooms or kitchens would reduce the need for chemical cleaners as well as saving effort.”

Soble reports that Dr. Ishida is not just interested in ceramic tile. The innovation that excites him most, Soble reports, “is a design for wings and fan-blades based on the uneven shape of dragonfly wings.” Soble explains:

“A cross-section of a dragonfly’s wing shows its paper-thin surface to be saw-tooth shaped like a ruffled potato crisp. This structure, Mr Ishida says, produces tiny whirling vortexes in the creases, which push air back, generate lift and give the wings ‘virtual’ volume without adding bulk or weight. Mr Ishida has incorporated the shape in wings he has designed for small, agile gliders – potential forerunners of ultra-lightweight aircraft. But the design may be even more useful in wind turbines, an increasingly popular yet fallible means of generating electricity. Prototype turbines built by Mr Ishida, using dragonfly-wing blades, keep on spinning even when winds drop to near-undetectable levels. ‘With this kind of efficiency it becomes feasible for every household to generate part of its own electricity with a small wind turbine,’ Mr Ishida says. ‘It changes the basic dynamics of power distribution.'”

I can envision how such efficient wind turbines could be especially useful in remote parts of developing countries where electrical grids are likely never to emerge. Reliable electricity could help them run water pumps, recharge mobile phones, light homes as well as refrigerate and cook food. Mother Nature is also inspiring some scientists to create a new type of battery [“Electrical potential,” The Economist, 12 December 2009 print issue]. The inspiration this time comes from the electric eel. The magazine reports:

“In December 2007 a Japanese aquarium hooked up the lights on a Christmas tree to a tank containing an electric eel. Metal plates at the ends of the tank enabled the eel to power the bulbs. It was certainly effective as a publicity stunt. Now some researchers in America have developed a battery that produces electricity in a similar way.”

The secret to the eel’s powerful punch is how it manages the flow of ions in its body. The article continues:

“Many creatures use differences in the concentration of ions (electrically charged atoms) within the body to do work. Human brains, for example, rely on electrical impulses to release calcium ions that bind to neurotransmitters that, in turn, communicate with the rest of the nervous system. The mechanism that allows Electrophorus electricus to produce a shock as strong as a wall socket employs differences in the concentration of sodium ions in some 6,000 specialized cells called electrocytes. These cells are normally electrically isolated from one another. When the eel locates its prey, it opens a series of cellular gates through which the ions flow. This movement of charged ions, when the eel is in a conductive solution like water, creates an electric current.”

According to the article, it was during the study of “living cell membranes and their proteins” that David LaVan of the National Institute of Standards and Technology in Maryland and his colleagues “realized that they might be able to copy the eel’s electricity-generation mechanism.”

“They began by experimenting on artificial ‘protocells’. These, like real cells, were surrounded by membranes made of fatty molecules. Proteins “floating” in the membranes would let only certain ions pass. … The team fused two protocells together, so that they shared part of their respective membranes. They then added a dilute concentration of potassium chloride to one protocell and a more concentrated solution to the other. The difference in concentrations of potassium and chloride ions would normally cause ions to move from the less concentrated protocell to the more concentrated one. In this case, however, the membrane between the protocells was too thick to permit much movement. Next, Dr LaVan and his colleagues installed a protein called alpha-hemolysin into the protocell membrane. This functioned as a selective bridge, permitting the passage of positively charged sodium ions, but not negatively charged chloride ions. As the selected ions moved in one direction, electrons (which are negatively charged) flowed in the opposite direction. To make use of this electrical current, the team connected tiny electrodes to the protocells. They report, in Advanced Materials, that they were able to sustain a usable current. Dr LaVan reckons that two of his protocells, measuring several centimetres across, could run a digital music-player for about 10 hours.”

Some day you may have to thank the lowly eel for keeping your MP3 player, digital watch, or cell phone running for longer periods of time. The medical field is another area where humans have learned from nature. The Economist reports that “an adhesive secreted by a marine worm inspires a promising new treatment for compound fractures of human bones” [“Glue bones,” 12 December 2009 print issue]. The magazine reports:

“Torn flesh is easy to put back together with stitches, but when bone breaks, repairs are nowhere near as simple. Bones with fractures that run in a straight line can often be placed back in their proper alignment and set in a cast to heal. Compound fractures, however—those that involve bones shattered into fragments—pose more of a challenge. Large fragments can, with the aid of metal screws and pins, be reattached and set in place for healing. Small fragments cannot be treated in the same way, as they are often too tiny to be connected with metal hardware. Medics have long sought a glue to do this work, and now Russell Stewart of the University of Utah may have found one in the secretions of a marine worm.”

The worm in question is the sandcastle worm and it lives in a mineral shell that it glues together rather than grows. It turns out that ions also play a role in how the sandcastle worm’s glue works. The article continues:

“[The sandcastle worm] secretes a glue and uses this to stick bits of sand together to form its casing. The glue does not dissolve in water. Indeed, it is able to displace water and thus adhere to surfaces even underwater. And it solidifies soon after being secreted. It, or something like it, therefore sounds ideal for repairing bones. Dr Stewart and his team began by analyzing sandcastle-worm glue to see how it works. What they found was a mixture of proteins, some positively charged and some negatively charged, and a lot of calcium and magnesium ions. The combination produces a material that can, when circumstances are right, bind the protein molecules so tightly together that any water molecules between them are expelled. The trigger for this to happen is a change in acidity. The gland in which the glue is generated is mildly acidic. In these circumstances the glue remains liquid. Seawater, however, is alkaline. This alkalinity causes the glue to set. It solidifies into a foam within 30 seconds and becomes a flexible, leathery substance over the course of several hours.”

The goal of any innovator involved in biomimicry is not only to be able to replicate nature’s wonders but to improve upon them. Dr. Stewart and his team believe they have done just that.

“Having understood how the sandcastle worm performs its trick, Dr Stewart was in a position to replicate it. Instead of proteins, he and his team used two synthetic polymers. These, however, had the same crucial chemical groups as their natural counterparts and similar electric charges. The result, as the team reported to a recent meeting of the American Chemical Society, was a substance even better, from a medical point of view, than the natural glue. Not only did it solidify in response to changes in acidity, it also did so in response to changes in temperature, being liquid at room temperature and solid at body temperature. The resulting glue not only sticks bits of bone together in watery environments, but also does so with twice the strength of the glue used by the worm. And, although it is still early days, preliminary tests suggest it is both non-toxic and biodegradable. If further testing confirms this, it means that, as the broken bone heals, the glue will disappear naturally. Compound fractures will thus heal more easily.”

Scientists and designers will continue to search nature’s storehouse for new ideas. I suspect the greatest breakthroughs will come when individuals from different fields discuss their work and explain wonders in nature that they have found. Such discussions will cause light bulbs to illuminate as new solutions to old problems are imagined.