Chinese scientists have created a camera which can spot a stressed person among a crowd in a bid to counter a spate of terror attacks by spotting those potentially about to commit a crime....(using) hyperspectral imaging to detect the amount of blood in oxygen and calculate stress levels. The scientists claim that they are able to distinguish between those with high oxygen levels due to physical activity and those caused by stress
Link:http://www.telegraph.co.uk/technolog...n-a-crowd.html

I am aware a number of private companies have offered pre-boarding screening devices, including one in Israel. Such a system would be very different from facial recognition systems already in - limited - use.