A finger-actuated microfluidic biosensor for colorimetric detection of foodborne pathogens

A microfluidic biosensor was developed for rapid detection of Salmonella using a finger-actuated micropump, a finger-actuated micromixer, [email protected] nanocatalysts ( [email protected] ) and a smartphone App. First, immune magnetic nanobeads (MNBs), bacterial sample and immune [email protected] were successively finger-actuated pumped into microfluidic chip. Then, they were fully mixed using finger-actuated micromixer to form MNB- Salmonella [email protected] complexes. After hydrogen peroxide-tetramethylbenzidine was pumped into chip and catalyzed by nanocatalysts on complexes, resulting in color change from colorless to blue, the image of catalysate was collected and finally analyzed by self-developed smartphone App or directly compared with Pantone color card in chip to determine   bacterial concentration. Experimental results showed this biosensor could quantitatively detect Salmonella from 3.5 × 10 2 to 3.5 × 10 5 CFU/mL in 1 h with lower detection limit of 350 CFU/mL. This biosensor has successfully integrated loading, mixing, incubation, washing, separation and detection onto a chip and might pave a promising way for bacterial detection.