The device uses technology designed by the attractively-named security researcher, Puking Monkey, that picks up the infrared light used by most CCTV cameras.
London-based artist, James Bridle, inserted the tech into a spaulder - a traditional component of medieval plate armour - to make it wearable.
When it detects a CCTV camera it notifies the wearer by pulsing a gentle electrical current through the shoulder which causes the muscles to twitch.
Unfortunately the device isn't quite functioning at the moment.
Birdle writes on his blog:
"Disclaimer: This is one of those much – and often fairly – maligned design fictions. The spaulder is not currently a functioning device, due to component shortages and electrical ineptness, hence the over-acting in the above video. Nevertheless, given the correct components and power supply, such a device is more than possible."
Birdle is also the man responsible for the Dronestagram project which uses social media to document drone strikes.