  Straintronic devices made of carbon-based materials have been pushed up due
to the graphene high mechanical flexibility and the possibility of interesting
changes in transport properties. Properly designed strained systems have been
proposed to allow optimized transport responses that can be explored in
experimental realizations. In multi-terminal systems, comparisons between
schemes with different geometries are important to characterize the
modifications introduced by mechanical deformations, specially if the
deformations are localized at a central part of the system or extended in a
large region. Then, in the present analysis, we study the strain effects on the
transport properties of triangular and hexagonal graphene flakes, with zigzag
and armchair edges, connected to three electronic terminals, formed by
semi-infinite graphene nanoribbons. Using the Green's function formalism with
circular renormalization schemes, and a single band tight-binding
approximation, we find that resonant tunneling transport becomes relevant and
is more affected by localized deformations in the hexagonal graphene flakes.
Moreover, triangular systems with deformation extended to the leads, like
longitudinal three-folded type, are shown as an interesting scenario for
building nanoscale waveguides for electronic current.
