Answer: Radio waves.
Scientists from Cornell University and Honeywell Aerospace may have the answer to developing devices that can be destroyed remotely should they fall into the wrong hands. Currently, devices with this ability, known as “transient electronics” require moisture, light or heat, all of which are difficult to build into technology and activate remotely.
This new method encases a microchip of silicon-dioxide in a polycarbonate shell. Rubidium and sodium biflouride are packed into microscopic cavities within the shell. These compounds are harmless while separated but react when mixed — the trick is getting them to do so. The team used radio waves, tuned to a specific frequency, to open tiny graphene-on-nitride valves between the cavities in the shell.
“The encapsulated rubidium then oxidizes vigorously, releasing heat to vaporize the polycarbonate shell and decompose the sodium bifluoride,” Cornell’s Ved Gund, who led the research team, told the Cornell Chronicle. “The latter controllably releases hydrofluoric acid to etch away the electronics.”