Pulling, Pressing, and Sensing with In-Flat: Transparent Touch Overlay for Smartphones

Smartphones' screens are touch-sensitive and offer rich visual output capabilities, but do not allow users to control a wide range of pressure input nor provide rich pressure sensations. We propose In-Flat, an input/output pressure-sensitive overlay for smartphones. In-Flat consists of a transparent inflatable skin-like silicon layer that can be placed on the top or the back of a smartphone. As an output device, In-Flat offers tangible affordances and dynamic pressure feedback coupled with visual display. As an input device, In-Flat enables users to continuously perform a wide range of input gestures, notably press and pinch-and-pull gestures. Thus, In-Flat can be used to finely manipulate visual objects in mobile interaction or mediate interpersonal touch communications. In contrast to previous studies that mostly focus on press, we investigated the performance of pinch-and-pull and compared it with press. Our experiment (N=12) showed that participants could perform pinch-and-pull (83.8%) as well as press (84.7%), but felt having more control when performing pinch-and-pull. We explored the use of In-Flat to enable multimodal interaction that couples visual display and touch input/output. Participants appreciated this coupling as well as the touch sensation supplied by the In-Flat device.