  Short-range experiments testing the gravitational inverse-square law at the
submillimeter scale offer uniquely sensitive probes of Lorentz invariance. A
combined analysis of results from the short-range gravity experiments
HUST-2015, HUST-2011, IU-2012, and IU-2002 permits the first independent
measurements of the 14 nonrelativistic coefficients for Lorentz violation in
the pure-gravity sector at the level of $10^{-9}$ m$^2$, improving by an order
of magnitude the sensitivity to numerous types of Lorentz violation involving
quadratic curvature derivatives and curvature couplings.
