We report transfer-free graphene growth on insulated substrates and the fabrication of a sensor array from the synthesized graphene. The insulated substrate coated with amorphous carbon and catalyst metals was annealed under an Ar atmosphere. After annealing, graphene was synthesized between the metal layer and the insulated substrate. We fabricated a sensing array based on the graphene growth method and used it for pH measurements. Our sensor had as a high resolution of pH as that of graphene synthesized by chemical vapor deposition. This technique allows graphene arrays to be synthesized simply and is suitable for industrial sensing applications. (C) 2016 Elsevier B.V. All rights reserved.