This work presents a novel and always-available nail mounted display known as NailDisplay. The proposed display augments the use of a finger by allowing for always-available visual feedback owing to its fast accessibility and binding user controls with the display, i.e. what you control is what you see (through the display). Potential benefits of NailDisplay are demonstrated in three applications: from displaying to combining it with user controls. In the first application, NailDisplay can reveal what is occluded under a finger touch, making it a solution to operate small UI elements. In the second application, NailDisplay is complementary to an imaginary interface, helping users to learn an imaginary interface (e.g., on the users' arms) and allowing them to reassure the interface when their memory of it becomes unclear. In the third application, NailDisplay is integrated with rich finger interactions, such as swiping in the air. We also report users' feedbacks gathered from an explorative user study.

We present FingerPad, a nail-mounted device that turns the tip of the index finger into a touchpad, allowing private and subtle interaction while on the move. FingerPad enables touch input using magnetic tracking, by adding a Hall sensor grid on the index fingernail, and a magnet on the thumbnail. Since it permits input through the pinch gesture, FingerPad is suitable for private use because the movements of the fingers in a pinch are subtle and are naturally hidden by the hand. Functionally, FingerPad resembles a touchpad, and also allows for eyes-free use. Additionally, since the necessary devices are attached to the nails, FingerPad preserves natural haptic feedback without affecting the native function of the fingertips. Through user study, we analyze the three design factors, namely posture, commitment method and target size, to assess the design of the FingerPad. Though the results show some trade-off among the factors, generally participants achieve 93% accuracy for very small targets (1.2mm-width) in the seated condition, and 92% accuracy for 2.5mm-width targets in the walking condition.

This work presents GaussSense, which is a back-of-device sensing technique for enabling input on an arbitrary surface using stylus by exploiting magnetism. A 2mm-thick Hall sensor grid is developed to sense magnets that are embedded in the stylus. Our system can sense the magnetic field that is emitted from the stylus when it is within 2cm of any non-ferromagnetic surface. Attaching the sensor behind an arbitrary thin surface enables the stylus input to be recognized by analyzing the distribution of the applied magnetic field. Attaching the sensor grid to the back of a touchscreen device and incorporating magnets into the corresponding stylus enable the system 1) to distinguish touch events that are caused by a finger from those caused by the stylus, 2) to sense the tilt angle of the stylus and the pressure with which it is applied, and 3) to detect where the stylus hovers over the screen. A pilot study reveals that people were satisfied with the novel sketching experiences based on this system.

This paper presents a novel interaction system, PUB (Point Upon Body), to explore eyes-free interaction in a personal space by allowing users tapping on their own arms to be provided with haptic feedback from their skin. Two user studies determine how users can interact precisely with their forearms and how users behave when operating in their arm space. According to those results, normal users can divide their arm space at most into 6 points between their wrists and elbows with iterative practice. Experimental results also indicate that the divided pattern of each user is unique from that of other ones. Based on the design principles from the observations, an interaction system, PUB, is designed to demonstrate how interaction design benefits from those findings. Two scenarios, remote display control and mobile device control, are demonstrated through the UltraSonic device attached on the users' wrists to detect their tapped positions.