Microfluidic Chip Based Microwell And Droplet Arrays For Cell Capture

This thesis is based on exploring the fundamental theory of microfluidic chip todevelop microstructures for high-throughput single-cell or cell-encapusulated dropletstrapping and afterwards cell analysing.By coming the fabrication process of microfluidic chip and microbeads’self-assembly phenomenon, microwell arrays for single cell trap and enzyme kineticanalysis were fabricated on PDMS replica. Self-assembled polystyrene microsphereswere melted on glass slide to enhance the adhensive force with the substrate, theupper part of the partically melted microspheres remained hemispherical and wassilanized to act as a reliable master. Two kinds of single cells were immobilizedwithin the traps and single cell enzyme kinetics study was carried out on the staticcells. This fabrication method is facile and cost effective with rounded bottomcontour specialty added; various cells with different diameters are able to beimmobilized on the arrays by choosing microspheres with matched sizes.A droplet-based microfluidic chip integrated with fast droplet generation andcapture function units was develped by devising novel microstructures arrays in thechannels, it is quite appropriate for the investigation of droplet encapusulated cells ina high-throughput manner. Monodispersed droplets were generated by T-junctionnozzles within microchannels with PDMS inner walls which prevented the dropletsfrom wetting the substrat and remain stable. In the downstream microstructure arrays,lots of droplets gradually entered the unoccupied captue voids and came toequilibrium in a self-stable manner with a capture efficiency above90%. Suchcaputure mode is suitable for high viscosity samples, because it alleviateed the highresistance of long channels which usually cost a long time for constant dropletgeneration. In the high-speed mode,blood droplets could be generated in a less than10min short time and all blood cells are retained in the droplet arrays.The advent of droplet based microfluidic technology has greatlly improved ourabilities of handling small volume samples, thus reduce reagent consumption and accelerated chemical reactions, both of which are suitable for high-throughputanalysis. Consequently, these two methods for cell capture may find applications incell-based biology, drup screening and cell communication.