Ultrahaptics

That little buzz you feel in your phone when you touch it... and it wants to be clear that you know you've done something is "haptic" feedback.

Ultrahaptics, has come up with a way to make you feel stuff without touching it. (I'm really curious to try this.) 

If true and pure gesture control is going to happen, I think this will be required-- otherwise it will be very difficult for software to figure out what all of our sloppy gestures mean.

This is a part of the whole ecosystem, and without this kind of feedback there will probably be an intermediate step to common gesture control (like the post yesterday.)