  We have laser cooled 3$\times10^6$ $^{87}$Rb atoms to 3$\mu$K in a
micro-fabricated grating magneto-optical trap (GMOT), enabling future
mass-deployment in highly accurate compact quantum sensors. We magnetically
trap the atoms, and use Larmor spin precession for magnetic sensing in the
vicinity of the atomic sample. Finally, we demonstrate an array of
magneto-optical traps with a single laser beam, which will be utilised for
future cold atom gradiometry.
