Existing haptic feedback on mobile phones, such as vibrotactile feedback, typically requires direct skin contact to ensure the notification receiving. In this paper, we present AirPalm, a phone-back mid-air haptic display that leverages this space between the phone back and the user’s palm to provide contact-free tactile feedback on the palm while the user is holding the phone. With this prototype, we conducted a series of psychophysical user-perception experiments. The results showed that our participants could identify various spatio-temporal haptic patterns with different intensities of airflow provided by AirPalm. Additionally, we conducted our final pattern-identification study in different usage scenarios, particularly in the situations of users watching video which could be considered as a distraction. Our results revealed a set of spatio-temporal airflow-based mid-air haptic patterns that could be identified by our participants with an overall accuracy above 85% while being engaged in different mobile-phone activities.

Authors: Yibin Huai, Lina Zhang, Zeshui Li, and Kening Zhu (*).