This study investigates the effects of uniaxial strain on graphene using Raman spectroscopy. Graphene sheets were deposited on a transparent and flexible substrate (polyethylene terephthalate, PET) and subjected to tensile strain up to ~0.8% by stretching the PET. The Raman spectra of strained graphene showed significant redshifts in the 2D and G bands (-27.8 cm⁻¹ and -14.2 cm⁻¹ per 1% strain, respectively), indicating the successful application of uniaxial strain. First-principles calculations predicted a bandgap opening of ~300 meV for graphene under 1% uniaxial tensile strain. The results suggest that strained graphene provides an efficient and controllable method to tune the bandgap, which could be more practical than other methods such as electric field tuning or molecule adsorption. The study also highlights the potential of flexible substrates and Raman spectroscopy as sensitive tools for strain measurement and tuning.This study investigates the effects of uniaxial strain on graphene using Raman spectroscopy. Graphene sheets were deposited on a transparent and flexible substrate (polyethylene terephthalate, PET) and subjected to tensile strain up to ~0.8% by stretching the PET. The Raman spectra of strained graphene showed significant redshifts in the 2D and G bands (-27.8 cm⁻¹ and -14.2 cm⁻¹ per 1% strain, respectively), indicating the successful application of uniaxial strain. First-principles calculations predicted a bandgap opening of ~300 meV for graphene under 1% uniaxial tensile strain. The results suggest that strained graphene provides an efficient and controllable method to tune the bandgap, which could be more practical than other methods such as electric field tuning or molecule adsorption. The study also highlights the potential of flexible substrates and Raman spectroscopy as sensitive tools for strain measurement and tuning.