Figure 2: Resonant frequency shifts at various concentration of S. typhimurium inoculated on tomatoes surfaces. S. typhimurium was inoculated in a square area (5 × 5 mm2) on tomato surfaces. A resonant frequency shift value represents 1/125 of total inoculated area, corresponding with the area of one ME sensor. Each data point represents the mean of triplicate samples taken from three replicate experiments (n=9).