Droplet microfluidics, in which aqueous droplets possessing volumes from nanoliters to femtoliters are used as individual biochemical reactors, has enabled a wide range of high throughput screening applications such as digital PCR, and screening of antibiotics. Our capability to form highly uniform drops at > 1kHz also enables us to generate complex fluids and soft matter bottom-up, and study how the microscopic structure of the material affects its bulk properties. Our research involves both fundamental and applied aspects:
(I) Flow physics of droplets and emulsions in confinements, and the origin of self-organization behavior.
(II) Applications including rapid detection of pathogens and directed evolution of functions from bacteria.
Selected publications: "Review and analysis of performance metrics of droplet microfluidics systems", Microfluidics and Nanofluidics, 16, 5, 921-939, 2014. ; "Break-up of droplets in a concentrated emulsion flowing through a narrow constriction", Soft Matter, 10, 421-430, 2014.
Inspired by biological optical systems (e.g., lenses) that can dynamically reconfigure shapes to fine-tune the optical properties (e.g., focal length), we have developed a new class of optics--"optofluidics" that is adaptive and can be reconfigured in real time. Recognizing that liquids are deformable, we demonstrated that it was possible to create functional optical devices—waveguides, lenses, dye lasers—using the interface between two liquids
Selected publications: “A multi-color fast-switching microfluidic droplet dye laser”, Lab on a Chip, 9, 2767 - 2771, 2009; “Dynamically reconfigurable liquid-core liquid-cladding lens in a microfluidic channel”, Lab on a Chip, 8, 395–401, 2008.
Inspired by tree rings—where the position of the ring indicates time, and the composition of the ring indicates historical environmental conditions—we are developing a new type of autonomous passive devices for simultaneous sensing and recording of time information. Initial applications can be in low-cost sensors such as smart labels to monitor the history of exposure to toxic chemicals in consumer/industrial safety products.
Wound healing and regeneration are essential biological processes for maintaining homeostasis and, ultimately, for survival. Cells, such as muscle cells, are regularly wounded in physiological conditions. These cells cannot be replaced easily in adults; self-healing is the only approach for restoring normal functions. Inability of a cell to heal can lead to serious diseases, such as muscular dystrophies. We are developing methods for controlled wounding and surgery of single cells, to enable systematic study of the biophysics behind wound healing and regeneration at the single-cell level.