Light-weight immaterial particle displays with mid-air tactile feedback

Immaterial mid-air displays formed of flowing light-scattering particles are becoming feasible for displaying information in thin air and interacting with it. With light-weight desktop fogscreens and low-cost hand tracking, the user can easily and unobtrusively interact with virtual information. Any real objects can be seen or reached through the screen, as it is permeable and almost intangible. However, no tactile feedback can be perceived when interacting with a mid-air display. Our contribution in this paper is the construction of an interactive mid-air fogscreen employing ultrasonic phased arrays in order to create mid-air tactile feedback. The feedback is suitable for small desktop-sized fogscreens. This creates a mixed reality setup where real objects and e.g., augmented reality content can be brought closer together conceptually and physically. In an experimental evaluation of the mid-air tactile feedback for the fogscreen we found no statistically significant difference in performance, but the mid-air tactile feedback was slightly preferred over no tactile feedback by the users. They found the tactile feedback as more engaging.