Controlled Fragmentation of Single-Atom-Thick Polycrystalline Graphene

Summary Controlling the fragmentation of atomically thin and brittle materials is of critical importance for both fundamental interest and technical purposes in fracture mechanics. However, the fragmentation of graphene is often random and uncontrollable because of the presence of grain boundaries and numerous defects. Here, by harnessing the strong localized strain during the necking process of thermoplastic polymers, we introduce a simple yet controllable method to tear apart a monolayer polycrystalline graphene (MPG) sheet into ordered graphene ribbons. More importantly, we show that the presence of active edges helps the graphene ribbons in exhibiting a field-effect characteristic pH response and improves the introduction of dopants. Furthermore, we demonstrate an optically transparent (∼98%), ultrathin (∼70 ± 15 nm), and skin-conformal pressure sensor for real-time tactile sensing. We believe that our results lead to further understanding of the fracture mechanics of graphene and offer unique advantages for practical applications, such as flexible electronics, chemical sensing, and biosensing.