What's the Latest Development?
By combining top-down and bottom-up approaches, a team of M.I.T. researchers has found a new way to create three-dimensional nanostructures—ones that have distinctive shapes and structures at scales of a few billionths of a meter—which have become a fertile area of research, producing materials that are useful for electronics, photonics, phononics and biomedical devices. A top-down approach is called phase-shift lithography, "in which a two-dimensional mask shapes the intensity of light shining onto a layer of photoresist material." The bottom-up approach uses "self-assembling colloidal nanoparticles that form themselves into certain energetically favorable close-packed arrangements."
What's the Big Idea?
This new way to form nanostructures will enable researchers to create a greater variety of forms and, eventually, uses for the budding technology. "Team members, whose specialty is in optics, say the first structures they plan to make are photonic crystals, whose structure can manipulate the behavior of light beams passing through them. But the method can also be used to make phononic materials, which control waves of heat or sound, or even to make filters with precisely controlled porosity, which might have biomedical applications."