A new 3D haptic display has been showed off by Prof. Takayuki Iwamoto and other researchers at the University of Tokyo. In their work, specially configured ultrasonic wave transducers create acoustic radiation force (or acoustic radiation pressure field) at a specific point in 3D space. Therefore, users can feel actual pressure (force) without touching the haptic display.
The prototype has a camera to track the position of a user's hand and modify ultrasonic waves to move the focal point around with the hand.
Currently, the system can create pressure field along the vertical direction.