Lightweight Wearable Fingertip Haptic Device with Tangential Force Feedback based on Finger Nail Stimulation

We present a lightweight wearable haptic device that provides tangential force feedback through fingernail stimulation. The device features a ring-like structure mounted on the fingernail side, incorporating three miniature motors: two for string-based force feedback in the distal-proximal direction and one with an arc-shaped pin for radial-ulnar stimulation. By relocating the actuators to the nail side, our design preserves the natural tactile sensitivity of the finger pad while achieving 2-DOF tangential force feedback. The device weighs only 5.24g and can generate nine distinct force patterns through the combination of string tension and pin pressure. We conducted preliminary user studies to evaluate direction discrimination and the ability to perceive different weights and friction coefficients.