Fig. 9

Real sample detection. a Fluorescence image of on-chip Salmonella spp. detection using spiked milk solutions. Limit of detection (LOD) test by changing the concentration of Salmonella spp. . The concentration of bacterium of Salmonella spp. of reaction chambers #1 ~ #5 in turn is:1.2 × 10⁴ CFU mL^− 1, 1.2 × 10³ CFU mL^− 1, 1.2 × 10² CFU mL^− 1, 1.2 × 10¹ CFU mL^− 1 and 1.2 × 10⁰ CFU mL^− 1. Chambers #1 and #2 contain the paper plate injected by the Salmonella spp. primer groups, #3 and #4 contain the paper plate loaded with the E. coli O157:H7 primer groups, #5 and #6 contain the paper plate loaded with the S. aureus primer groups, #7 and #8 contain the paper plate injected by the V. parahaemolyticus primer groups respectively. b Results of gel electrophoresis (the lane number corresponds to the PC plate number). c A graph shows the fluorescence intensity of each type of bacteria measured under different concentrations of the initial DNA template