Four electrodes are attached to players' forearms and, in conjunction with a prototype iOS game, can make players involuntarily tilt their phone, creating a sensation of force feedback.
Players using the system find themselves fighting against involuntary movements in their arms and hands. In Lopes's demonstration video, those movements correspond to on-screen events during a flight game.
But this sort of haptic feedback isn't created by a miniature motor. Instead, it's what Lopes and Baudisch are calling "muscle-propelled force feedback."
The system has been booked in for a demonstration at the CHI 2013 conference in Paris, April 27 - May 2, the same congress that members of Microsoft's Kinect team will be attending.