This borders on ridiculous:

Chinese scientists are developing a mini-camera to scan crowds for highly stressed individuals, offering law-enforcement officers a potential tool to spot would-be suicide bombers.

[…]

“They all looked and behaved as ordinary people but their level of mental stress must have been extremely high before they launched their attacks. Our technology can detect such people, so law enforcement officers can take precautions and prevent these tragedies,” Chen said.

Officers looking through the device at a crowd would see a mental “stress bar” above each person’s head, and the suspects highlighted with a red face.

The researchers said they were able to use the technology to tell the difference between high-blood oxygen levels produced by stress rather than just physical exertion.