When delivered through a vibrating motor in a controller or smartphone, force feedback isn't particularly realistic. So researchers at Germany's Hasso Plattner Institute have developed a new system for smartphones that uses electrical muscle stimulation to physically move the player's hands and forearms in response to the action happening on screen.
The stimulation causes the user's palm flexor muscle to contract, which in turn causes the phone to tilt to the left or right. And in order to succeed in a custom flight simulator game, the players who tested the system had to fight back and counteract these involuntary movements.
The shocks used are apparently completely painless, and the electrodes that allow it to interact with the user could be easily integrated into a compact smartphone case. [Pedro Lopes Research via Hasso Plattner Institut via NewScientist]