Counting of Escherichia coli by a microflow cytometer based on a photonic-microfluidic integrated device

Counting of Escherichia coli DH5 alpha-cell suspensions in PBS is performed using a microflow cytometer based on a photonic-microfluidic integrated device. Side-scattered light signals are used to count the E. coli cells. A detection efficiency of 92% is achieved when compared with the expected count from a hemocytometer. The detection efficiency is correlated to the ratio of sample to sheath flow rates. It is demonstrated that E. coli can be easily distinguished from beads of similar sizes (2-4 mu m) as their scattering intensities are different.