GE's metallic ink can put tiny sensors inside jet engines
Source: http://www.engadget.com/2014/06/10/ge-direct-write/
GE is already testing Direct Write sensors with some of its partners, and it notes that the technique could apply sensors to devices well after they've left the factory. However, the technology isn't flawless; while the ink may survive hostile environments, wireless signals typically don't. It may be a long while before you can fit sensors in places where even wires are too risky.
Via: Wall Street Journal
Source: GE Reports