Highly integrated microdevice for ultrasensitive pathogen detection

We present here a miniaturized lab-on-a-chip (LOC) system that integrates cell capture and preconcentration, polymerase chain reaction (PCR), and capillary electrophoresis (CE) for pathogen detection. For efficient cell capture on a chip, we used an optimized bifurcated microfluidic channel design and a pumping flutter scheme to isolate target cells, E. coli K12 and E. coli O157, in a fluidized bed of immunomagnetic beads. The cell captured beads are transferred using a on-chip pump to the 100 nL of PCR reactor for DNA amplification. The produced PCR amplicons are subsequently electrophoretically injected into a 5-cm long CE column for separation. The E. coli O157 target was identified with a detection limit of 0.2 cfu/μL. Even in a 1000-fold excess background of E. coli K12 cells, the 100 cfu E. coli O157 was successfully detected, demonstrating high sensitivity and capability of real-world sample analysis.