  We show that when the pseudomagnetic fields created by long wavelength
deformations are appropriately coupled with a scalar electric potential, a
significant energy gap can emerge due to the formation of a Haldane state.
Ramifications of this physical effect are examined through the study of various
strain geometries commonly seen in experiments, such as strain superlattices
and wrinkled suspended graphene. Of particular technological importance, we
consider setup where this gap can be tunable through electrostatic gates,
allowing for the design of electronic devices not realizable with other
materials.
