Office of Technology Transfer – University of Michigan

Force Sensing Based on Structure-Borne Sound Propagation

Technology #6928

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Kang Geun Shin
Managed By
Drew Bennett
Associate Director - Software Licensing 734-615-4004
Patent Protection
US Patent Pending

As mobile devices such as smartphones become increasingly indispensable during everyday life, improved user interfacing becomes more critical to enhancing user experiences with their devices. More improved input methods can create new ways of interaction that can provide entertainment or improve quality of life. However, such methods that require new sensors can be cost-prohibitive and breaks backwards compatibility with older devices. A new method of structural force detection using sound propagation may provide a method of accepting user inputs without such costly new additions.

Force detection using built-in microphones and speakers

The new technique can be implemented in software on existing devices by accessing the speaker and microphone. A special high frequency signal beyond human hearing range is generated by the speaker and measured by the microphone as its vibration travels through the body of the device. The vibration pattern changes based on the amount of force a user exerts while gripping or pressing on the device. This method can produce up to 97% bi-level force detection and at significantly higher peak force levels than existing capacitive touch sensors in current devices. Integration into operating systems and applications could open new gestures for mobile device control.


  • Mobile operating systems
  • Mobile applications


  • High peak force detection
  • Compatible with any device featuring a speaker and microphone
  • Low cost of implementation