UbiTouch: Ubiquitous smartphone touchpads using built-in proximity and ambient light sensors

Smart devices are increasingly shrinking in size, which results in new challenges for user-mobile interaction through minuscule touchscreens. Existing works to explore alternative interaction technologies mainly rely on external devices which degrade portability. In this paper, we propose UbiTouch, a novel system that extends smartphones with virtual touchpads on desktops using built-in smartphone sensors. It senses a user's finger movement with a proximity and ambient light sensor whose raw sensory data from underlying hardware are strongly dependent on the finger's locations. UbiTouch maps the raw data into the finger's positions by utilizing Curvilinear Component Analysis and improve tracking accuracy via a particle filter. We have evaluate our system in three scenarios with different lighting conditions by five users. The results show that UbiTouch achieves centimetre-level localization accuracy and poses no significant impact on the battery life. We envisage that UbiTouch could support applications such as textwriting and drawing.