i3lock, the go-to locker for i3wm, does not support unlocking with fingerprint scanners. Until now, that is :) To unlock your linux computer by simply scanning your fingerprint, install fprintd and then use this script instead of i3lock to lock your session:

i3lock &
(while pidof i3lock; do
  if (fprintd-verify | grep verify-match); then 
    killall i3lock
  fi
done) &