  For more than 30 years, the remarkable superconducting properties of
REBa$_\textrm{2}$Cu$_\textrm{3}$O$_\textrm{7-x}$ (RE = rare earth) compounds
have triggered research studies across the world. Accordingly, significant
progresses have been made both from a basic understanding and a fabrication
processes perspective. Yet, today, the major technological bottleneck towards
the spread of their practical uses remains the exponential decay of their
critical current with grain misorientation in polycrystalline samples. In this
work, we used an ionic liquid to apply extremely high transverse electric
fields to YBa$_\textrm{2}$Cu$_\textrm{3}$O$_\textrm{7-x}$ thin films containing
a single well-defined low-angle grain boundary. Our study shows that this
technique is very effective to tune the IV characteristics of these weak-links.
In-magnetic field measurements allow us to discuss the type of the vortices
present at the grain boundary and to unveil a large variation of the local
depairing current density with gating. Comparing our results with the ones
obtained on chemically-doped grain boundaries, we discuss routes to evaluate
the role of local strain in the loss of transparency at cuprates low-angle
grain boundaries. In short, this study offers a new opportunity to discuss
scenarios leading to the reduced transport capabilities of grain boundaries in
cuprates.
