Pulp Friction - Exploring the Finger Pad Periphery for Subtle Haptic Feedback.

Current haptic feedback techniques on handheld devices are applied to the finger pad or the palm of the user. These state-of-the-art approaches are coarse-grained and tend to be intrusive, rather than subtle. In contrast, we present a new feedback technique that applies stimuli around the periphery of the finger pulp, demonstrating how this can provide rich, nuanced haptic information. We use a reconfigurable haptic device employing a ferromagnetic marble for back-of-the device handheld use, which, for the first time, probes, without instrumenting the user, the periphery of the distal phalanx with localised stimulation. We present the design-space afforded by this new technique and evaluate the human-factors of finger-peripheral touch interaction in a controlled user-study. We report results with marbles of different diameters, speeds and a combination of poking, lateral vibration and patterns; present the resulting design guidelines for finger-periphery haptic feedback; and, illustrate its potential with use case scenarios.