Mona Zebarjadi

In 1965, Intel co-founder Gordon Moore noticed that the number of transistors per square inch of integrated circuit doubled roughly every two years. Moore’s Law posits that this trend would continue into the foreseeable future — and it has. Certainly the ability to hold a smartphone in the palm of your hand — in the process availing yourself of the computing power of a circa-1990 supercomputer — is a testament to Moore’s prescience.

Thermoelectric devices — which can either generate an electric current from a difference in temperature or use electricity to produce heating or cooling without moving parts — have been explored in the laboratory since the 19th century. In recent years, their efficiency has improved enough to enable limited commercial use, such as in cooling systems built into the seats of automobiles. But more widespread use, such as to harness waste heat from power plants and engines, calls for better materials.

The design of artificial metamaterials that allow “cloaking”—apparent invisibility to acoustic and electromagnetic waves—is more than a party trick. Many applications suggest themselves if one could create cloaking at useful frequencies or in technologically relevant systems. Writing in Physical Review Letters, Bolin Liao and colleagues at Massachusetts Institute of Technology, Cambridge, propose the use of cloaking in semiconductor devices to optimize electron mobility in nanostructured materials.