PhantomFolds: Exploring Unobtrusive Spatial Tactile Feedback Produced by Two Fingernail Mounted LRAs for In-Air and On-Surface Mixed Reality Applications

To support seamless mixed reality (MR) interactions without obstructing natural touch, we introduce PhantomFolds, a nail-mounted device featuring two linear resonant actuators (LRAs) at the lateral nail folds that provide spatio-tactile feedback for in-air as well as on-surface interactions in MR. In three studies, we investigate the perception of spatio-tactile feedback produced by PhantomFolds. Our results show that (1) PhantomFolds can leverage the funneling illusion to produce spatio-tactile feedback at the finger for in-air as well as on-surface interactions, (2) tactile feedback produced with PhantomFolds can successfully increase the perceived realism in MR applications without impeding user interaction, (3) phantom sensations, are perceived more localized when users touch a surface, and (4) while participants could not consistently feel touch illusions below the finger when touching a surface as described by prior work, our results indicate that a per-user calibration could increase the success rate of this effect in the future.