The Application Of Droplet Microfluidic In Microorganism Separation And Analysis

Micro fluidics is the science and technology which deal with chemical and biological fluids accurately at the microscale. Droplet microfluidics is an important branch of microfluidics generates and manipulates highly monodisperse droplets, emulsions, double emulsions, and bubbles. It is ideal for performing chemical and biochemical reactions in droplets. Droplet microfluidics has been widely used in diverse areas as drug screening, protein crystallization, digital PCR, and single cell analysis.Droplet digital PCR (ddPCR) is a new approach to nucleic acid detection that surpasses conventional real-time quantitative PCR for absolute quantification and rare allele detection. In chapter 2, we developed a ddPCR device which integrates flow focusing droplet generation, droplet array storage, and droplet imaging after thermal cycling. The device was made simply by the assembly of two glass plates with etched microstructures. We would use this device in pathogen detection in drinking water. Our method provided a highly solvent compatible device for ddPCR with possibility to reuse the device with simple washing treatment after each use.Single-cell sorting based on metabolic activity of bacterial cells are recently emerged as an effective approach for microbial breeding. In chapter 3, a high-throughput microfluidic chip system is developed for sorting of lactic acid producing bacterial cells based on pH-responsive hydrogel droplets. Picoliter droplets were generated on chip containing bacterial cells, sodium alginate, and calcium carbonate nanoparticles. The droplets are incubated at 38? to allow growth of single cells in the droplets. Gelation occurred in those droplets containing lactic acid producer, as calcium carbonate nanoparticles are dissolved by the decrease of pH value, and sodium alginate were crosslinked with calcium ions. Following incubation, a novel device was introduced for sorting droplets based on stiffness. This pH-responsive single-cell sorting strategy might be widely used for microbial breeding of organic acids producing microbial species of industrial importance.