We tried out the Ultrahaptics interface at CES, and it is genuinely extraordinary. The first demo fires a stream of invisible bubbles at your hand, which burst when you come into "contact" with them; they don't feel exactly like soap bubbles, popping with a gentle buzz, but they're close enough to the real thing that it makes no odds.
A second demo has you playing a brick-and-bat game, with a pulse firing at your hand each time the ball makes contact with the bat. There's also a vertical "force field" which you can push your hand through air – it feels something like the stream of air that issues forth from a Dyson Airblade.
You can instantly see the potential for gaming and entertainment applications – imagine feeling the wind on your face, or raindrops, while watching a movie or playing a game.

It's the final demo, though, that's most interesting – pointing to the possibilities of the device as a control interface. The computer screen shows a spinning circular dial which, when you put your hand above the ultrasound generator, is matched by a pulse that traces a circle on your hand. Move your hand about, and it tracks your hand's position, following you about. Trace circles in the air with your hand, and the circular motion speeds up.




One of the problems faced by control interfaces like the Leap Motion and Kinect is a lack of tactile feedback – as anyone who's flailed about in front of their Xbox One will testify.
The Ultrahaptics generator could solve that problem, giving you a physical response to a gesture-controlled system; it could be particularly useful for controlling the infotainment system in a car, for example.
We'll be watching Ultrahaptics with interest – and hopefully it won't be long before we're getting our hands on (or above) it in a commercially-available product.