Attracting Fingers with Waves: Potential Fields Using Active Lateral Forces Enhance Touch Interactions

Touchscreens and touchpads offer intuitive interfaces but provide limited tactile feedback, usually just mechanical vibrations. These devices lack continuous feedback to guide users’ fingers toward specific directions. Recent innovations in surface haptic devices, however, leverage ultrasonic traveling waves to create active lateral forces on a bare fingertip. This paper investigates the effects and design possibilities of active forces feedback in touch interactions by rendering artificial potential fields on a touchpad. Three user studies revealed that: (1) users perceived attractive and repulsive fields as bumps and holes with similar detection thresholds; (2) step-wise force fields improved targeting by 22.9% compared to friction-only methods; and (3) active force fields effectively communicated directional cues to the users. Several applications were tested, with user feedback favoring this approach for its enhanced tactile experience, added enjoyment, realism, and ease of use.