Demo: Augmenting Force-Sensing Interface to Mobile Devices with Sound

We present ForcePhone, a novel system of enabling commodity phones to recognize the force applied to their touch screen and body. Researchers have shown the usefulness and importance of this expressive input interface (especially for the one-hand operation), but this advanced function has not yet been realized and deployed in most state-of-the-art smartphones. Instead of augmenting specialized/proprietary sensors, ForcePhone uses only the phone's built-in sensors to measure the applied force via a physical property called structure-borne sound propagation. ForcePhone has been implemented and evaluated on both iOS and Android phones. Multiple demo applications based on ForcePhone have been implemented and tested. The estimated force is shown highly correlated to the real applied force and the estimation error is low enough to support various applications. Most participants in our usability study were able to master the ForcePhone-based apps and find them very useful.