  We fabricate monolayer MoS2 field effect transistors and study their electric
characteristics from 10^-6 Torr to atmospheric air pressure. We show that the
threshold voltage of the transistor increases with the growing pressure. Hence,
we propose the device as an air pressure sensor, showing that it is
particularly suitable as a low power consumption vacuum gauge. The device
functions on pressure-dependent O2, N2 and H2O molecule adsorption that affect
the n-doping of the MoS2 channel.
