“…As the UME approaches the surface, the decreasing gap between the UME and the surface hinders diffusion to the UME surface. While ferrocene species, including ferrocene methanol (FcMeOH), are nontoxic to some cells, the presence of these mediators means that other molecules, such as H 2 O 2 , cannot be measured accurately in their presence due to overlapping current signals ( 40 ). Thus, there is a need to develop alternative methods for approaching the surface of biofilms.…”