  Pursuing ultrasensitivity of pressure sensors has been a long-standing goal.
Here, we report a piezoelectric sensor that exhibits supreme pressure-sensing
performance, including a peak sensitivity up to 3.5*10^6 kPa^-1 in the pressure
range of 1-100 mPa and a detection limit of less than 1 mPa, superior to the
current state-of-the-art pressure sensors. These properties are attributed to
the high percentage of periodic atom vacancies in the two-dimensional Na2Cl
crystals formed within multilayered graphene oxide membrane in the sensor,
which provides giant polarization with high stability. The sensor can even
clearly detect the airflow fluctuations surrounding a flapping butterfly, which
have long been the elusive tiny signals in the famous "butterfly effect". The
finding represents a step towards next-generation pressure sensors for various
precision applications.
