MURRAY HILL, N.J., Feb. 21 -- Borrowing an approach from Mother Nature, scientists from Lucent Technologies' Bell Labs have created high-quality, complex-shaped crystals that could potentially find applications in communications networks and other devices in the future.
The ornate crystals of calcite are the latest product of an emerging field of science known as biomimetics, which takes engineering principals from the natural world and applies them to man-made materials and technologies. Described in a research paper in today's issue of the journal Science, the crystals are fabricated by a novel technique that involves depositing the mineral in such a way that each single crystal contains intricate microscopic patterns. It is an approach that may have broad implications for materials science and nanotechnology, the researchers say.
"I have always been fascinated with nature's ability to perfect materials," said Joanna Aizenberg, the Bell Labs materials scientist who led the research. "The more we study biological organisms, the more we realize how much we can learn from them. We recently discovered that nature makes excellent micro-patterned crystals, and we decided to see if we could copy the natural approach in the lab, since this technique may be useful in nanotechnology."
About two years ago, Aizenberg and her colleagues made the surprising discovery that thousands of calcite crystals spread throughout the exoskeletons of brittlestars, starfish-like marine invertebrates, collectively form an unusual kind of compound eye for the animals. The brittlestar's calcite microlenses expertly compensate for birefringence and spherical aberration, two common types of distortions in lenses. This led the Bell Labs scientists to attempt to mimic nature's success and design crystals based on the brittlestar model, with the ultimate goal of building complexes arrays of microlenses like the brittlestar's.
Today lenses are typically made using a "top down" approach, in which a piece of glass is ground down to a lens' exact specifications. The brittlestar, on the other hand, makes its microlenses using a "bottom up" approach, in which successive layers of calcite are deposited onto an organic template in intricate patterns to form perfect crystalline lenses at the temperature of seawater.
"This is an excellent example where we can learn from Nature," said Cherry Murray, senior vice president of physical sciences research at Bell Labs. "In this case, a relatively simple organism has a solution to a very complex problem in integrated optics and materials design. By studying the brittlestar, we can learn about low-cost ways of forming single crystals in complex shapes at low temperatures. While many years from commercial use, this understanding could be very important to fabrication of nano-patterned materials."
Aizenberg and colleagues David Muller, John Grazul and Don Hamann studied biomineralization principles and developed a new crystallization approach that allowed them to directly fabricate single crystals of calcite that were about one-tenth of a centimeter across, with patterns less than ten micrometers across, which is approximately one-tenth the diameter of a human hair.
The new Bell Labs approach may revolutionize how crystals are made in the future for a wide variety of applications. Single crystals patterned at the micron scale or smaller and integrated into opto-electronic circuits are important components in various electronic, sensory and optical devices.
For more information, visit: www.bell-labs.com