Metamaterials
First demonstrated in 1999 by a group of researchers led by physicist David R. Smith, metamaterials are now on the cusp of transforming entire industries. The term generally refers to synthetic composite materials that exhibit properties not found in nature. What Smith demonstrated was the ability to bend light waves in directions—described as “left-handed”—not observed in natural materials.
As a field of engineering metamaterials are perhaps the clearest evidence that we are in the midst of a materials revolution that goes far beyond the impact of computing and communications.
The concept has been speculated about for more than a century, particularly in the work of Russian physicist Victor Veselago during the 1960s. However, the results of Smith’s group touched off a new wave of excitement and experimentation in the scientific community. The notion captured the popular imagination briefly some years ago with the discussion of the possibility of invisibility cloaks, however, today it is having a more practical impact across the entire electromagnetic spectrum.
It may soon transform markets such as the automotive industry, where there is a need for less expensive and more precise radars for self-driving vehicles. Metamaterial design has also begun to yield new classes of antennas which will be smaller in size while also being more powerful, tunable, and directional.
Some of the uses are novel, such as a transparent coating that can be applied to cockpit windshields, serving to protect pilots from harassing lasers beamed from the ground. This is already a commercial reality. Other applications are more speculative, yet still promising. Several years ago scientists at the French construction firm Menard published a paper on describing a test of a novel way of counteracting the effects of an earthquake from a metamaterial grid of empty cylindrical columns bored into soil. They reported that they were able to measure a significant dampening of a simulated earthquake with the array of columns.
While Harry Potter invisibility shields may not be possible, there is clear military interest in metamaterials for new stealth applications. DARPA has a project exploring the possibility of armor for soldiers that would make them less visible, and it is possible that such technology could be applied to vehicles such as tanks.
Another promising area that may soon be transformed by the ability to create what is known as a “negative refractive index”—not found in nature, might be so-called “superlens” enabling microscopes that reach past the resolving power of today’s scientific instruments. They also promise the ability to filter and control sound in news ways. That holds out the possibility of new kinds of ultrasound devices, peering into the human body with enhanced three-dimensional resolution.
Researchers note that the application of these synthetic materials far outstrip the imagination and that new applications will appear as engineers and scientists rethink existing technologies.
Perhaps Harry Potter invisibility is far-fetched, but several years ago Xiang Zhang, a UC Berkeley nanoscientist, speculated that it might be possible to make dust particles disappear in semiconductor manufacturing. By inserting a metamaterial layer in the optical path of the exotic light waves now used to etch molecular-scale transistors, it might be possible to make the contamination effectively invisible. That in turn would lead to a significant jump in the yield of working chips. And it conceivably might put the computer industry back on the Moore’s law curve of ever-more-powerful computing.
