The electrochemical detection process of Salmonella is shown in Fig. 1. The GCE electrode was first modified with GO and GNPs to im- prove the electron transfer effect. Then, it was incubated with the Salmonella-specific recognition aptamer to construct the aptamer- based electrochemical biosensor. Finally, this composite structure was immersed in different dilutions of Salmonella. With more Salmonella in the detection system, the electron transfer between the electrode and electrolyte was more inhibited and resulted in a smaller current and a higher resistance. These values could be quantified by EIS measurement.