  In this paper we discuss design concepts for increasing the spatial
resolution, improving the sensitivity, and reducing the invasiveness in
scanning Superconducting Quantum Interference Device (SQUID) microscope sensors
with integrated flux pickup loops. This can be done not only by reducing the
ground-rule line widths and spacings, but also by taking advantage of
planarization, reducing flux noise through reducing the SQUID inductance, and
reducing back-action through dispersive readouts or on-chip filtering.
