Modern alchemy makes materials 'smart'

In labs across the US, new products display a human mastery overmatter.

When a helicopter chatters loudly overhead in Boston, most people look up and see the police or a traffic reporter.

But Harry Tuller sees ceramics. That's because the Massachusetts Institute of Technology scientist is working on a revolutionary type of helicopter rotor that can continuously change shape in midflight when zapped with electrical charges. These rotors, made of a new class of materials called electroceramics, could improve the performance and reliability of helicopter flight.

Mr. Tuller's electroceramics are just one of a myriad of so-called "smart materials" that are increasingly emerging from labs and being used to enhance performance, safety, and efficiency in a wide range of industries.

*Hybrid ceramic materials are embedded in snow skis to dampen vibrations and smooth out the ride on the slopes.

*JCPenney stores are using super-thin display signs that look like paper but contain words and numbers spelled out with thousands of pigment-filled capsules made of a new type of electrically sensitive plastic. These display signs, which can be reconfigured remotely, are a likely precursor to portable newspapers that are constantly updated with wireless data transmissions.

*Eyeglass frames made of "memory" metal alloys return to their original shape when a certain temperature threshold is passed.

These gee-whiz materials are merely the start of a new era in which humanity will achieve stunning mastery over matter.

"Only in the last decade, with the advent of more-powerful computers, have we started to acquire the tools for trying to predict in advance the relationship between a property and a structure," says Tuller.

Knowledge is power

Knowledge seekers have long coveted greater control over the materials that make up the world. Medieval alchemists futilely attempted to synthesize gold from lesser elements. And failure to understand the nature of matter and the chemical elements has proven disastrous. In the 19th century, physicians regularly prescribed heavy metals like arsenic as remedies, which sometimes proved fatal.

But when people have gained some mastery of crucial materials, they have changed the course of history. Magnetic lodestones, for example, allowed Chinese sailors to create navigational compasses, which led to the first transoceanic explorations.

But this pales in comparison to the threshold scientists stand upon today. For the first time ever, researchers can examine complex matrixes of molecules and predict how changing them will alter their properties.

This new and far deeper understanding of how matter acts and reacts enables scientists to create materials that are not static but rather reactive and malleable in relation to factors such as temperature, electrical currents, or physical stress.

"A smart material can tell you something about a situation or a state of affairs by responding in a predictable way to some kind of stimulus," explains Art Ellis, a chemist at the University of Wisconsin at Madison.

Smart and intuitive

Unlike past advances in material science, which have been far more piecemeal, the current onslaught covers many fronts, from ceramics to metals to plastics. And it is churning out discoveries at an astonishing rate.

Hand in hand with smart materials go recent advances in reducing the size of microprocessors and computers. Scientists are now hard at work integrating the two to create powerful systems that can be embedded in everything from clothing to performance-enhancing spark plugs.

But some smart materials are so intuitive that they actually will eliminate the need for microprocessors that now generally control things like air bags or other mechanical processes.

The US Navy has created a diving wet suit with tiny wax capsules embedded in its material. The capsules melt at just below body temperature, taking heat from the skin of a diver who is putting on the dry suit, and storing it. The heat is preserved in these capsules and later shields the diver against cold water and keeps the suit comfortable longer.

The same method of regulating temperature is also used in boots. "When we put our finger on a hot stove, we pull it back from the stove. A really smart material system is like that. It is one in which there is an automatic response in the right direction without a lot of additional microprocessing power," says Tuller.

Computer-as-laboratory

Integral to this shift to smart materials has been rapid increases in computing power. Real-world environments are often too impure or too expensive for accurate laboratory experiments with these new materials.

Rather, scientists are finding it far easier to model materials on computers first and then take their results to the bench. "Now the models have gotten more sophisticated, the computers much more powerful, and we are starting to see some really predictive capabilities in some areas. More and more experiments will be done in the computer rather than in the laboratory," says Tuller.

As computer modeling has come into its own, scientists are also applying these new techniques to study how to make traditional materials smarter.

"Even the low-tech materials we take for granted are chemically rather complex and we still don't know how they behave," says Alistair Cormack at Alfred University in New York. "We have been able to analyze structures of glasses in a much more detailed way. Some people are looking at the fracture process of glass at the atomic level."

And the atomic level is precisely where the material science field appears headed. Tunneling electron microscopes now allows scientists to physically move individual molecules and even atoms.

Three weeks ago scientists at UCLA and Hewlett-Packard announced they had built "logic gates" on a molecular level into a crystal of man-made material called rotaxane. These gates are the on-off structures that describe the binary nature of bits of information and are the most fundamental part of computer processors. This discovery opened the realm for powerful computers far smaller than what the human eye can see and far faster than anything known today.

"We have this unprecedented control over matter on this nanoscale," says Mr. Ellis. "The idea of being able to make materials in a controlled way on this scale is just remarkable."

(c) Copyright 1999. The Christian Science Publishing Society

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