  With the emergence of pen-enabled tablets and mobile devices, stylus-based
interaction has been receiving increasing attention. Unfortunately, styluses
available in the market today are all passive instruments that are primarily
used for writing and pointing. In this paper, we describe a novel stylus
capable of displaying certain vibro-tactile and inertial haptic effects to the
user. Our stylus is equipped with two vibration actuators at the ends, which
are used to create a tactile sensation of up and down movement along the
stylus. The stylus is also embedded with a DC motor, which is used to create a
sense of bidirectional rotational torque about the long axis of the pen.
Through two psychophysical experiments, we show that, when driven with
carefully selected timing and actuation patterns, our haptic stylus can convey
movement and rotational torque information to the user. Results from a further
psychophysical experiment provide insight on how the shape of the actuation
patterns effects the perception of rotational torque effect. Finally,
experimental results from our interactive pen-based game show that our haptic
stylus is effective in practical settings
