Single-bacterium resolution biosensors based on pristine graphenes

We investigated the sensing abilities of pristine graphene based nanosensors in response to the attachment of Escherichia coli (E. coli) to the graphene surfaces. Using pristine graphenes, instead of functionalized graphenes, helps us understand better the influence of E. coli cells on the transport properties of graphenes. The biosensors based on pristine few-layer graphenes showed a discriminable response to the attachment of an individual E. coli cell, indicating the sensing ability with single-bacterium resolution. Furthermore, higher sensitivities were achieved using pristine mono-layer graphenes and graphene microribbons as the sensing materials. The higher sensitivities can be attributed to the elimination of the interferences from inessential graphene layers and the quantum confinement in the graphene microribbon.