AAWSAP DIRD, Aerospace Applications of Programmable Matter, December 2009

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products may be both cheaper than, and of superior quality to, those produced by the
aerospace industry.
Assuming this trend holds true across the next four decades and applies even to exotic
technologies such as programmable materials, it is logical to suppose that consumer
applications such as smart windows and multispectral night-vision sensors are more
likely to spin off to the aerospace industry than the reverse. Therefore, advancement of
smart materials technology for aerospace applications will likely depend on research
and development for consumer applications. In addition, the "low-hanging fruit"
applications, with the largest markets and thus the highest profit potential, will have
the greatest accelerant effect on the technology.
Therefore, near-term applications such as smart windows and energy-saving
metapolarizers, which offer direct and immediate economic advantages (namely energy
savings) and which dovetail neatly with existing infrastructure, should be considered
the most promising for research over the next 5 years.
Over the longer term, a number of problems must be overcome for fully programmable
material devices to be constructed. In the case of metamaterials, the primary challenge
is fabrication. Numerous nanopatterning techniques have been developed for producing
regular patterns on a surface, including grids, gratings, and patterns of dots or holes.
However, the resonant properties of metamaterials typically require more complex
structures that are not easily mass produced on the scales necessary for optical
wavelengths-typically 100 nanometers or less, and often as little as 10 nanometers.
Promising candidate technologies include nanoindentation lithography, extreme
ultraviolet photolithography, and photolithography using metamaterials-based
"superlenses." Liquid crystal technology is more mature, but to survive in the harsh
environment of outer space, it may need to evolve higher resistance to ultraviolet and
other forms of ionizing radiation,
Perhaps the most promising long-term technology is the addressable quantum dot
array. However, for broadly programmable applications-particularly in aerospace-the
issue of temperature sensitivity must be brought under control. This may involve direct
temperature control of the active surfaces or development of high-bandgap material
systems for which the coefficient of thermal expansion and bandgap versus
temperature slope are both small, In addition, shielding the metallic nanostructures
against interference from stray electric or magnetic fields will be very important and
may rely on as-yet-undeveloped techniques or materials (for example, high­
temperature superconductors),
However, the vast potential of programmable materials and devices, as well as the
clear advantages they hold in certain earthly and aerospace applications where
traditional material limitations clearly constrain functionality, should not be
underestimated. Building and vehicle skins, sensors, and windows are three areas that
particularly lend themselves to enhancement with multifunctional materials, and the
commercial advantages of developing these will be considerable. As with transistors,
LEDs, LCDs, integrated circuits and other late 20th century technologies, the economic
imperatives are likely to overcome many significant technological barriers, and by 2050
it seems likely that our grandchildren will have difficulty imagining a world where these
objects are made from traditional, inert materials. Their relationship to material objects
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