Tunable Phase Change on Nanoengineered Surfaces
Using a combined theoretical and experimental approach, we conduct in-depth investigation of the dynamic interaction of water of different states (vapor, liquid, solid) and phase change (condensation, boiling, evaporation, and frosting/defrosting) heat transfer. The fundermental knowledge learned from these studies, especially the elucidation of the role of surface roughness and wettability on nucleation, growth, spreading, coalescence and departure in phase change, offers important insights in surface design.
Microfluidic Instrumentation for Biomolecular Diagnosis
We can combine the droplet manipulation and fluorescence based detection techniques for high-throughput and highly sensitive analysis of droplet content. Using an integrated droplet microfluidic platform, we demonstrated on-chip droplet-based digital PCR for absolute quantification of rare genes with a wide dynamic range (Biomicrofluidics, 2018). We extended the standard ELISA with our droplet digital PCR techniques to droplet-based single-exosome-counting enzyme-linked immunoassay for identifying membrane protein biomarkers and digital quantification of the target exosomes (Nano Letters, 2018).
Microfluidic Synthesis of Bionanomaterials
Droplet microfluidics enables the generation of highly uniform emulsions with excellent stability, precise control over droplet volume and morphology, which offer superior platforms over conventional technologies for material synthesis and biological assays. We show that robust and scalable generation of uniform droplets using a multilayer device formed by stacking layer-by-layer of the polydimethylsiloxane (PDMS) replica patterned with parallelized generators for synthesis of polyacrylamide hydrogel and Poly (l-lactide-co-glycolide) (PLGA) through water-in-oil (W/O) and oil-in-water (O/W) emulsion templates (Micromachines, 2019).
Microfluidic Mixing for Studies of Molecular Self-Assembly
We developed a laminar flow microfluidic mixer that enables real-time monitoring ultrafast kinetics with microsecond resolution for millisecond range. This novel device allows us to investigate molecular conformational change and intermolecular interactions (e.g., protein folding and nanoparticle self-assembly). We combined the ultrarapid hydrodynamic focusing microfluidic mixer and the time-resolved fluorescence resonance energy transfer measurement to map the very early folding pathway of a protein, cytochrome c, with temporal resolution at microsecond level and structural resolution at Angstrom level (Analytical Chemistry, 2015).
