  We investigate the effects of uniaxial strain on the transport properties of
vertical devices made of two twisted graphene layers, which partially overlap
each other. We find that because of the different orientations of the two
graphene lattices, their Dirac points can be displaced and separated in the
$k-$space by the effects of strain. Hence, a finite conduction gap as large as
a few hundred meV can be obtained in the device with a small strain of only a
few percent. The dependence of this conduction gap on the strain strength,
strain direction, transport direction and twist angle are clarified and
presented. On this basis, the strong modulation of conductance and significant
improvement of Seebeck coefficient are shown. The suggested devices therefore
may be very promising for improving applications of graphene, e.g., as
transistors or strain and thermal sensors.
