AirPalm: Exploring Airborne Haptic Feedback from Phone-Back Airflow on the Palm

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.