ABSTRACT
At present, touchscreens can differentiate multiple points of
contact, but not who is touching the device. In this work,
we consider how the electrical properties of humans and
their attire can be used to support user differentiation on
touchscreens. We propse a novel sensing approach based on
Swept Frequency Capacitive Sensing, which measures the
impedance of a user to the environment (i.e., ground) across
a range of AC frequencies. Different people have different
bone densities and muscle mass, wear different footwear,
and so on. This, in turn, yields different impedance profiles,
which allows for touch events, including multitouch gestures,
to be attributed to a particular user. This has many
interesting implications for interactive design. We describe
and evaluate our sensing approach, demonstrating that the
technique has considerable promise. We also discuss limitations,
how these might be overcome, and next steps.