and an LOD of 1.6 x 10 -8 M was achieved for this label-free technique. Importantly, the researchers demonstrated the selectivity of the sensor with a PCR product from STEC and Salmonella. reported a sensor for the detection of lacZ gene sequence of E. coli using reporter DNA tagged with methylene blue (MB). As in the previous study, the thiol modified probe DNA was immobilized onto a gold surface and the surface and the DNA hybridisation was measured via alternating current voltammetry (ACV). In this study, an LOD of 3x10 -14 M was obtained and the sensor was validated their using synthetic DNA spiked milk, beer, tap water, and peanut milk, in order to demonstrate the pH and ionic strength dependency of the sensor. The sensor was regenerated six times after hybridisation in milk samples by rinsing it with DI water for 60 seconds which may be a promising result for the continuous monitoring. The real application should, however, be also tested using DNA extracted from bacterial cultures or naturally contaminated samples.