Guest Seminar - Precision Condensation in Space and Time

Due to the intrinsic lack of spatial order and self-supported shape, liquids are often incompatible with precision manufacturing / processing and are potentially limited for advanced functionality. Herein, we develop an optothermal strategy to fully command phase-separated liquids with unprecedent spatiotemporal addressability. Specifically, we focus a laser onto an Au film to create a hot spot that locally demixes a temperature-responsive solution to produce a single optothermal droplet. Spatial precision (~ 1 micron) is assured by the well-defined thermal field and temporal accuracy (~ 0.1 s) guaranteed by the fast heating and response rate. Time-multiplexed laser foci are deployed to engineer the thermal landscape as desired, which in turn dictates the formation/dissolution, positioning, shaping, and dynamic reconfiguration of the phase-separated liquids. We further program laser foci to orchestrate the liquid patterns in a time-continuous manner to produce liquid animations on the microscale with high fidelity. While focused laser has been routinely used to manipulate solid particles or to microfabricate solid materials, the current strategy embraces the merits of liquid and features functional complexity in information encryption, payload transportation, and reaction localization. We expect it to be further applicable in scenarios such as subcellular organization of biomolecular condensates and programmable modulation of nonequilibrium systems.