Monolayer graphene chemiresistive biosensor for rapid bacteria detection in a microchannel

Bacteria, such as Escherichia coli (E. coli), can cause food poisoning and serious diseases. In fact, E. coli has emerged multiple times as a severe public health concern in recent years. Therefore, it is important to detect bacteria like E. coli in simple, rapid and sensitive approaches. In this study, a gate-free chemiresistive biosensor based on monolayer graphene (MG) is proposed to detect E. coli, thanks to the high sensitivity stemming from the anti-E. coli antibody-coated graphene. The immobilization of the antibodies is performed via streptavidin and biotin conjugation on the graphene surface. Compared to conventional bacterial biosensors, the proposed chemiresistive biosensor captures the E. coli bacteria on the surface of the sensor and performs the detection through electric readouts, other than optical signals. That is the resistance measured in the biosensor increases along with the increase of concentration of the bacteria. To further extend the capabilities of this biosensor and provide a controllable test flow, a microchannel is integrated on the graphene surface. The results show that the developed chemiresistive biosensor is able to detect E. coli in trace concentration down to 12 cfu ml−1, indicating an excellent sensing performance. The proposed monolayer graphene based chemiresistive biosensor clearly manifest its advantages of low-cost, ease of fabrication, portability and good sensitivity, as well as the potential for rapid in-situ bacterial detection.