Nano Nano

An Internet guide to the nanoworld

gecko foot
© Bujak

In 1959, the physicist Richard Feynman (known for safecracking at Los Alamos, bongo playing, and his insights into quantum electrodynamics) gave a talk at Caltech entitled, “There’s Plenty of Room at the Bottom.” That prophetic lecture is often cited as the beginning of nanoscience, the study of matter at the scale of one billionth of a meter. At Nanowerk, I found a video, Kavli Foundation: An Introduction to Nanoscience, in which narrator Alan Alda explains how Feynman’s seminal thoughts were sparked by his interest in cellular biology. Feynman figured nature had been in the nanotechnology business for billions of years, and eventually we would be too. Through the trial and error of evolution, life has engineered some remarkable devices, such as the bacterium’s spinning motor that it uses for propulsion, and the ultra-fine, spatula-shaped hairs that allow a gecko’s foot to stick to glass.

Before getting to other general sites on the nanoworld, let’s start with the gecko, which has become, in the nano-age, the poster child for “bioinspiration.” Humans have always looked to nature to get ideas for building tomorrow’s machines, but the process, also called “biomimetics,” is particularly useful in the world of the very small. Three TED lectures by biologist
Robert Full at the University of California at Berkeley offer a wonderful look into how biologists and engineers have worked together to reproduce the gecko’s remarkable climbing abilities. The first lecture is on animal movement. In the next, Full discusses evolution and engineering. The third, and most recent, is unexpectedly titled “Learning from the Gecko’s Tail”—that fifth appendage turns out to be equally important to the gecko’s motion in a number of surprising ways. But the animal’s feet remain its most impressive feature. Depending on the species, they come in many sizes shapes and colors: check out the images at Kellar Autumn’s Lab at Lewis and Clark College in Portland, Oregon. For an article on a carbon-nanotube-based glue inspired by the gecko’s foot, see Nanotechnology Mimics Nature’s Adhesive.

The butterfly’s wing is another major source of inspiration for nanotechnologists. The colors on the insects’ wings are produced by nano-scale structures instead of pigments, so researchers are interested in copying them, replacing today’s pigments that may be toxic or costly. See Butterflies Provide Clues for Replacing Color Pigments with Photonic Nanocrystals. For another article on the special optical properties of butterfly wings (and peacock feathers) go to Peacock Feathers and Butterfly Wings Inspire Bio-templated Nanotechnology Materials. The blueprint for minute sensors may also be hidden in the scales of the butterfly wing. Go to GE Scientists Discover that Nanostructures on the Surface of Butterfly Wings Exhibit Acute Chemical Sensing Capabilities to read about researchers who discovered that the nanostructures on scales have just the right high-performance optical properties to make extremely sensitive vapor detectors. The butterfly’s wing is also evolved to be extraordinarily dirt and water repellant. Go to Butterfly Wing Trick Could Make Self-Cleaning Windows a Reality to read about French research that may lead to crystal-clear windows. And finally there is the light emitting Diode (LED). Although engineers recently developed this miracle of modern lighting, researchers at the University of Exeter in England have found that LEDs Work Like Butterflies’ Wings. Apparently, the fluorescent patches on the wings of African swallowtails function just like LEDs, and they evolved the ability some 30 million years ago.

Spiders are another goldmine of inspiration for the nanotechnologists, from the minute hairs on their feet (see this news article) to the stronger-than-steel silk used in their webs. And the applications are often unexpected. See Spider Silk Delivers Finest Optical Fibres. Arachnids may help bring about the tiny, fast connections that make computers with optical circuits practical.

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