In addition to light sensors, gyroscopes, and accelerometers, did you know most tablets and smartphones have a built in magnetometer? Its immediate benefit might not be obvious, but as this video demonstrates, it could let you use magnets to interact with your devices instead of boring old fingers or styluses.

It turns out the hardware already built into these devices is able to distinguish the strength and position of a magnet with a usable amount of accuracy. And as researchers Andrea Bianchi and Ian Oakley from the University of Madeira and Carnegie Mellon Europe have discovered, it allows you to build physical objects that can interact with a smartphone or tablet in ways a regular stylus can't. For example, with magnets in each tip, a drawing app could recognize when a stylus was being used to draw or erase. Although, weren't we all taught that magnets and electronics don't mix? [Andrea Bianchi via Make]