"We are able to measure activities that originate deeper in the brain from the surface without penetrating the brain, " said materials engineer George Malliaras at the Microelectronics Center of Provence in France, who led the research team.

WSJ: Brain Science: Mysterious Neural Circuitry Becomes Viewable

"The thing you need to engineer into the materials is very different behaviour in different directions that the wave travels through it, " he told BBC News.

BBC: Acoustic 'cloaking device' shields objects from sound

Williams met Li, a mining engineer, in 1997 while running a construction materials firm in Tianjin.

FORBES: Cat Scammed: How A U.S. Company Blew Half A Billion Dollars In China

The scheme saw engineer regiments construct airfields as part of the soldiers' training using materials supplied by local authorities.

BBC: Skye airstrip study set to get Highland Council funds