A necklace fob has been designed to stop people leaving phones or laptops behind in a cafe – or stop thieves who have taken a gadget from using it.
Most portable electronic devices have one thing in common: they rely on a battery, says Norwegian inventor Rolf Hansen in patent application W0 2004/40886. So Hansen has combined the battery with a “watchdog” component that keeps the battery working only while it is receiving a unique code from an ultra-low power radio transmitter worn on a necklace.
When the communication fails, the battery bleeps a warning, saves any open files and then…
