ForcePhone: Software Lets Smartphones Sense Touch Force

To enhance the input capability on the severely limited space of a phone's screen, touch force has been a vital way to expand user-phone interactions. For example, users can get an options menu by hard-pressing a button or can surf the previous webpage by squeezing the phone. 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. Unlike many other proposals, which require the addition of specialized hardware, the authors propose a software-based solution called ForcePhone. Their solution exploits a well-known physical property, called structure-borne sound propagation, to enable commodity phones to recognize the force applied to their touchscreen and body.