Non-contact tactile sensation synthesized by ultrasound transducers

This paper describes a new tactile device which produces stress fields in 3D space. Combined with mid-air and/or 3D stereoscopic displays, this device provides high-fidelity tactile feedback for interaction with visual objects. The principle is based on a nonlinear phenomenon of ultrasound; acoustic radiation pressure. The fabricated prototype device consists of 324 airborne ultrasound transducers, and the phase and intensity of each transducer are controlled individually. The total output force within the focal region is 1.6 gf. The spatial resolution is 20 mm. The prototype can produce sufficient vibrations up to 1 kHz. An interaction system including the prototype is also introduced which tracks user's hand and provides suitable touch feeling.