Smartwatches to soon follow finger commands in mid-air

As wearable devices grow and screens shrink, a team of Indian-origin researchers has developed a new sonar technology that allows you to interact with smarwatches by writing or gesturing on any nearby surface — a tabletop, a sheet of paper or even in mid-air.
Called FingerIO, it tracks fine-grained finger movements by turning a smartphone or smartwatch into an active sonar system using the device’s own microphones and speakers.
Because sound waves travel through fabric and do not req