A microfluidic system for rapid enrichment and sensitive detection of E. coli based on bilayer membrane and high flux droplets

Rapid and sensitive detection of Escherichia coli (E. coli) is crucial for ensuring water safety. Traditional culture-based detection technologies are time-consuming, cumbersome, and difficult to meet immediate needs, while existing instrument-based detection is costly, time-consuming, and struggle to process complex samples. Herein, a microfluidic system for rapid enrichment and sensitive detection of E. coli in water based on bilayer membrane and high flux droplets is proposed. The bilayer membrane structure can enrich bacteria while removing impurities in the sample. High-throughput droplets can encapsulate single bacteria for enzymatic reactions within the droplets, reducing the reaction system to nanoliter, and greatly shortening the reaction time. The results showed that the detection of E. coli solution with different concentrations by this system had little difference compared to the plate counting method, demonstrating a good linear relationship (R = 0.9968) and the detection of total coliform in sewage has an accuracy rate of at least 80 %. In summary, this system combines enrichment technology with microdroplet technology to detect E. coli for the first time. It can achieve 50-fold enrichment of E. coli in water and bacteria isolation in 100 μL solution with tens of thousands of droplets, which greatly improves the sensitivity and efficiency of detection, thus showing great potential for ensuring water safety.