  Gradient fields can effectively suppress particle tunneling in a lattice and
localize the wave function at all energy scales, a phenomenon known as Stark
localization. Here, we show that Stark systems can be used as a probe for the
precise measurement of gradient fields, particularly in the weak-field regime
where most sensors do not operate optimally. In the extended phase, Stark
probes achieve super-Heisenberg precision, which is well beyond most of the
known quantum sensing schemes. In the localized phase, the precision drops in a
universal way showing fast convergence to the thermodynamic limit. For
single-particle probes, we show that quantum-enhanced sensitivity, with
super-Heisenberg precision, can be achieved through a simple position
measurement for all the eigenstates across the entire spectrum. For such
probes, we have identified several critical exponents of the Stark localization
transition and established their relationship. Thermal fluctuations, whose
universal behavior is identified, reduce the precision from super-Heisenberg to
Heisenberg, still outperforming classical sensors. Multiparticle interacting
probes also achieve super-Heisenberg scaling in their extended phase, which
shows even further enhancement near the transition point. Quantum-enhanced
sensitivity is still achievable even when state preparation time is included in
resource analysis.
