What Do a Toucan, an Oyster and a Spider Have in Common? Bio-Engineers' Drool
If we want to build more robust, lightweight materials, two researchers say, look to nature.
Spider silk is extraordinarily strong, mollusk shells and bone are tough, and porcupine quills and feathers resist buckling. How are these notable properties achieved? The building blocks of the materials listed above are primarily minerals and biopolymers, mostly in combination; the first weak in tension and the second weak in compression. The intricate and ingenious hierarchical structures are responsible for the outstanding performance of each material. Toughness is conferred by the presence of controlled interfacial features (friction, hydrogen bonds, chain straightening and stretching); buckling resistance can be achieved by filling a slender column with a lightweight foam. Here, we present and interpret selected examples of these and other biological materials. Structural bio-inspired materials design makes use of the biological structures by inserting synthetic materials and processes that augment the structures’ capability while retaining their essential features. In this Review, we explain this idea through some unusual concepts.
Meyers & McKittrick delineated the following challenges for materials engineers: self assembly, multi-functionality, hierarchy, hydration, mild synthesis conditions (e.g., room temperature), optimization, and self-healing. For inspiration, they looked to the beak of the toucan, the feathers of birds, oyster shells, spider silk, porcupine quills, and the skulls of longhorn cowfish. Strong, lightweight, durable – life has mastered all seven design specifications. Engineers don’t have to use proteins as long as they follow the methods used in nature. “Mother Nature gives us templates,” said McKittrick. “We are trying to understand them better so we can implement them in new materials.”
Meyers pointed out that biomimetics has a long history. “Bio-inspired designs have been a part of science and engineering for a long time—from the legend of Icarus, to Leonardo Da Vinci‘s flying machines, inspired by birds, to modern-day materials such as Velcro, Meyers pointed out” in PhysOrg. Only in the last decade or so has the field really taken off, with new research labs, journals and dramatic successes with more on the way all the time.
In other Biomimetics news, (1) Science discussed efforts to copy what microbes do so easily—splitting hydrogen molecules. Hydrogenase enzymes are the envy of fuel cell designers but molecular biologists still don’t know quite how they work so effectively at room temperature. (2) PNAS featured “Biomimetic Buildings” in a review that is part engineering, part art, and part Thoreau. Architect Charles Lee’s exhibit of a biomimetic house is currently on tour as part of exhibition entitled Nature’s Toolbox: Biodiversity, Art, and Invention. (3) Finally, Science Daily talked about “Cell Circuits Remember Their History: Engineers Design New Synthetic Biology Circuits That Combine Memory and Logic.” By building logic circuits in the genes of bacteria, MIT researchers hope to create “long-term environmental sensors, efficient controls for biomanufacturing, or to program stem cells to differentiate into other cell types.”
The future is in biomimetics, not Darwinism. The quaint Victorian myth has no place in this exploding field. Get with the program, Charlie worshippers; it’s all about design now.