  We investigate the longitudinal and transverse piezoresistance effect in
suspended graphene in the ballistic regime. Utilizing parametrized tight
binding Hamiltonian from ab initio calculations along with Landauer quantum
transport formalism, we devise a methodology to evaluate the piezoresistance
effect in 2D materials especially in graphene. We evaluate the longitudinal and
transverse gauge factor of graphene along armchair and zigzag directions in the
linear elastic limit ($0\%$-$10\%$). The longitudinal and transverse gauge
factors are identical along armchair and zigzag directions. Our model predicts
a significant variation ($\approx 1000\% $ change) in transverse gauge factor
compared to longitudinal gauge factor along with sign inversion. The calculated
value of longitudinal gauge factor is $\approx 0.3$ whereas the transverse
gauge factor is $\approx -3.3$. We rationalize our prediction using deformation
of Dirac cone and change in separation between transverse modes due to
longitudinal and transverse strain, leading to an inverse change in gauge
factor. The results obtained herein may serve as a template for high strain
piezoresistance effect of graphene in nano electromechanical systems.
