The advantage of using the whole-cell detection is the lack of need for DNA extraction, however, the sensor may not be as specific to recognise STEC as a nucleic acid-based detection. In both studies, STEC was recognised using aptamers and the final detection was based on a stem-loop structure probe DNA tagged with MB immobilised onto a gold electrode. In the work of , STEC recognition by a specific aptamer triggered a primer exchange reaction (PER) which initiated the synthesise of ssDNA strands (PER product) leading the activation of Cas12a. The enzyme led to the creaking of the stem-loop structure probe DNA on the electrode and therefore, a current decrease related to MB which was detected by using DPV. The authors developed a highly sensitive sensor with a LOD of 19 CFU/mL, with an analysis time of fewer than three hours.