Dissertation Defense: Jingyu Wu

LARGE-SCALE MICROFLUIDIC MANUFACTURING OF GRANULAR HYDROGELS AND MULTIPLE EMULSIONS

Abstract:

Droplet microfluidics have made tremendous progress in the last two decades in the generation of micrometer- and nanometer-scale materials. One of the major developments lies in the incorporation of multiple microfluidic devices onto single chips enabling emulsion generation at clinical and industrial-relevant scale. However, most demonstrated successes have focused on producing simple emulsions; production upscaling of complex emulsion and materials have not been realized. In this thesis, I will demonstrate new approaches and some early successes to fill this gap between lab-scale and industrially relevant scale production of complex emulsion and drop-based on-chip material synthesis. First, a silicon-and-glass based microchip is developed for ultrahigh throughput on-chip photopolymerization of microgels. We demonstrate that the mechanical properties of microgels can be modulated by tuning the UV dosage and a massive parallelization of 4080 microfluidic synthesis lines on a 4-inch wafer. Second, a new wettability patterning strategy, along with the fabrication process, is developed to pattern the hydrophobicity of a silicon-based microfluidic chip. We demonstrate wettability patterning with micrometer resolution and generation of both W/O/W and O/W/O double emulsions. Further, the scalability of this approach is demonstrated with chips that incorporate 50 parallelized double-emulsion generating devices, producing double emulsions in a high throughput manner (26.5 kHz double emulsions). Lastly, we extend the above approach and develop a novel approach to perform surface wettability patterning via polymer enrichment and replica molding (SUPER), controlling the wettability of microfluidic channels made of a solvent-resistant PFPE-PEG copolymer network. We demonstrate the utility of this approach by fabricating a PFPE-PEG based microfluidic chip, with hydrophobic/hydrophilic patterned microchannels, to generate double emulsions.