A new sonar technology developed by computer scientists and electrical engineers allows you to interact with mobile devices and smartwatch screens by writing or gesturing on any nearby surface, a tabletop, a sheet of paper or even in mid-air.

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A new sonar technology developed by computer scientists and electrical engineers allows you to interact with mobile devices and smartwatch screens by writing or gesturing on any nearby surface, a tabletop, a sheet of paper or even in mid-air.