“Researchers at the University of Washington’s aptly named Ubiquitous Computing Lab can turn any LCD monitor in your house into a touchscreen, with nothing more than a $5 sensor that plugs into the wall and some clever software.
“The technology, called uTouch, works by measuring the electromagnetic interference (EMI) caused by your hand when it moves near or touches an LCD monitor. This might sound a little bit crazy, but I’ll explain. Basically, the electricity running through the wires in your house has a unique electromagnetic signature. There is the “carrier wave,” provided by the power company and your nearby substation, and then every single kink and switch along the way modulates the EM signature until it is quite unique. What most people don’t realize, though, is that every device that is plugged into a wall outlet also changes your EM signature. Your TV doesn’t just suck power from your house — it’s a two-way street, with the electronic components in the TV producing interference that change your house’s EM signature.”