This paper reports the results of an exploratory study into inadvertent grip pressure changes on mobile devices with a focus on the differences between static lab-based and mobile walking environments. The aim of this research is to inform the design of more robust pressure input techniques that can accommodate dynamic mobile usage. The results of the experiment show that there are significant differences in grip pressure in static and walking conditions with high levels of pressure variation in both. By combining the pressure data with accelerometer data, we show that grip pressure is closely related to user movement.

ForcePhone is a mobile synchronous haptic communication system. During phone calls, users can squeeze the side of the device and the pressure level is mapped to vibrations on the recipient's device. The pressure/vibrotactile messages supported by ForcePhone are called pressages. Using a lab-based study and a small field study, this paper addresses the following questions: how can haptic interpersonal communication be integrated into a standard mobile device? What is the most appropriate feedback design for pressages? What types of non-verbal cues can be represented by pressages? Do users make use of pressages during their conversations? The results of this research indicate that such a system has value as a communication channel in real-world settings with users expressing greetings, presence and emotions through pressages.