Overview
The goal of this work was to develop new useful applications for a smartphone fingerprint
sensor. I generated interaction ideas, implemented a Wizard-of-Oz demo, ran sessions of think
alouds & card sorting, and analyzed results. The goal was to use the highly sensitive touch data
from the fingerprint sensor to enable useful smartphone interactions. This takes advantage of
the fingerprint sensor’s ergonomic location by using gestures to expand its usefulness beyond
simply unlocking the device.
Methods
The research sessions consisted of semi-structured interviews with ten participants, each
lasting about 30 minutes. Initially I interviewed people about their general smartphone use and
interactions. This was followed by a card sorting exercise and think aloud, which dove into the
specific proposed gestures and interactions. This was accompanied by a Wizard-of-Oz demo that I
implemented because a working demo was not available at the time. I built demos in HTML and
controlled them using a Bluetooth keyboard to communicate with the smartphone. When the
participants had assigned a gesture to an interaction, this allowed them to try it out in a
realistic fashion. Finally, participants provided ratings and verbal comments for each gesture.
Outcome
General reactions to the proposed concepts were positive and the study revealed a few gestures
that were viewed favorably by most participants, as well as possible actions to
initiate using those gestures. Results were presented and shared with other researchers,
engineering, and product marketing teams. About a year after this work was completed and shared,
several phones entered the market with features exactly like those explored in this research.
The results were also published as late-breaking work at the CHI conference in 2016, and received a Best Paper Honorable Mention award.
Links
Example of a participant’s final card sort, showing mappings between gestures and interactions.
Participants' average ratings for the six proposed gestures. Ultimately double tap and swipe left/right were the most preferred gestures.