Fig. 8.

The entire operation workflow. a Processed and ready PC sheet; b insert the paper soaked by LAMP reagent and calcein in every reaction chamber, where the manganese ion conducts the fluorescence quenching for calcein; c extract the DNA of salmonella from the marked milk by using the coated paper on the basis of thermal decomposition and polydopamine; d After centrifugation, the polydopamine-coated paper in the sample chamber will capture milk protein and cell debris, and the purified DNA is averagely thrown to the reaction chamber; e put the PC microchip on the heater to heat at 65 °C for heating for 30 min; f after the LAMP reaction is over, the pyrophosphate ion combines with the manganese ion to release the calcein and thereby the green fluorescence will be emitted in the UV radiation