Figure 6.

(a–d) Schematic circuitry to illustrate the proposed mechanism for the observed phenomena of different responses of bacteria to the graphene films in darkness (a) on conductor Cu (b), semiconductor Ge (c) and insulator SiO₂ (d) substrates from the view of the energy band diagrams of these graphene-on-substrate junctions; (e–h) Schematic illustration for the electrical measurements (e) to obtain the current–voltage (I–V) characteristics of Graphene@Cu (f), Graphene@Ge (g) and Graphene@SiO₂ (h) contacts at room temperature, respectively, indicating three different contacts of graphene films with the underlying substrates.