The authors developed a method to produce high-quality, wafer-scale graphene films up to 3 inches in size on Ni and Cu substrates under ambient pressure. These films were then transferred to arbitrary substrates through the instantaneous etching of metal layers. The method demonstrated the batch fabrication of field-effect transistors (FETs) and stretchable strain gauges, achieving hole and electron mobilities of 1,100 ± 70 cm²/Vs and 550 ± 50 cm²/Vs, respectively, at a drain bias of -0.75V. The piezo-resistance gauge factor of the strain sensor was approximately 6.1. This approach significantly advances the scalability and processibility of graphene films for wafer-scale devices and flexible/stretchable electronics. The study highlights the potential of large-area graphene in optoelectronics and flexible electronics.The authors developed a method to produce high-quality, wafer-scale graphene films up to 3 inches in size on Ni and Cu substrates under ambient pressure. These films were then transferred to arbitrary substrates through the instantaneous etching of metal layers. The method demonstrated the batch fabrication of field-effect transistors (FETs) and stretchable strain gauges, achieving hole and electron mobilities of 1,100 ± 70 cm²/Vs and 550 ± 50 cm²/Vs, respectively, at a drain bias of -0.75V. The piezo-resistance gauge factor of the strain sensor was approximately 6.1. This approach significantly advances the scalability and processibility of graphene films for wafer-scale devices and flexible/stretchable electronics. The study highlights the potential of large-area graphene in optoelectronics and flexible electronics.