The Stack Archive

ForcePhone app uses ultrasonic tone to create pressure-sensitive Batphone

Fri 27 May 2016


Researchers at the University of Michigan have created an app that makes any smartphone pressure-sensitive without additional hardware. The app, called ForcePhone, uses ultrasonic tones in the existing microphone and speaker hardware that respond to pressure for additional functionality for touchscreens.

The app emits a high-frequency ultrasound tone from the device’s existing microphone, which is inaudible to humans but can be picked up by the phone. That tone is calibrated to change depending on the pressure that the user gives on the screen or on the body of the phone. This gives users an additional way to interact with their device through the app alone.

The additional functionality provided by ForcePhone can be used in a number of ways. Squeezing the body of the phone could take a user back a page, for example; or increased pressure on the touchscreen could act as a ‘right-click’ function, showing additional information on the app in use. Kan Shin, Professor at the University of Michigan, said, “You don’t need a special screen or built-in sensors to do this. Now this functionality can be realized on any phone.” He added, “We’ve augmented the user interface without requiring any special built-in sensors. ForcePhone increases the vocabulary between the phone and the user.”

ForcePhone is the third in a series of apps inspired by 2008’s The Dark Knight, in which Batman turns Gotham City’s smartphones into a sonar system to track the Joker. Yu-Shih Tung, the PhD student who created the app with Shin, said, “I thought it was an interesting idea to turn smartphones into a sonar-based system and felt this could lead to new applications to address challenges faced by smartphone users.”

The first app inspired by the idea was BumpAlert, which uses the phone’s speaker and microphone to create an acoustic detector to warn distracted pedestrians of objects in their path. It was followed by EchoTag, which uses sonar to identify specific locations and assign those locations specific tones or tasks.

While ForcePhone is still in the testing phase, Shin and Tung plan to present an update at a conference in Singapore next month.


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