You may not have heard of it before, but haptic technology is all around us. The buzz of your smartphone as you tap the keys, or the rumble of your Wii controller as you smash a tennis ball are both haptic effects. But this touch feedback technology has uses far beyond enhancing your game experience; it’s used in rehabilitation of stroke patients and even surgical training. Now, scientists have invented a new method of haptic feedback using ultrasound, which creates 3D haptic shapes in mid-air that can be seen and felt.
The researchers, who are based at the University of Bristol, envisage that this innovative technology could transform the way that we use 3D haptic shapes. It could lead to touchable holograms to augment learning, or enhanced gaming experience by allowing users to feel features of the game, such as a football. It could even have a place in medicine, for example by allowing surgeons to physically feel tumors by exploring CT scans.
The method, which is described in ACM Transactions on Graphics, exploits an effect produced by ultrasound called acoustic radiation force, which is the scattering and absorption of the acoustic wave. By observing how sound waves behave when they hit an object, it is possible to deduce the shape of the object. The team also realized that it is possible to feel these shapes by focusing complex patterns of ultrasound onto our hands. In doing so, the researchers created air disturbances that could be felt on the skin and seen as floating 3D shapes. The ultrasound patterns cannot be seen by themselves, but the team visualized them by directing the device at a layer of oil so that depressions at the surface appeared as spots when illuminated.
By adding these invisible 3D shapes to 3D displays, scientists can create something that can be both seen and felt. The team also demonstrated that users were able to match images of a 3D shape to the shape produced by the device.