Optothermally Programmable Liquids with Spatiotemporal Precision and Functional Complexity

Abstract

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, an optothermal strategy is developed to fully command phase‐separated liquids with unprecedented spatiotemporal addressability. Specifically, a laser is focused onto an Au film to create a hot spot that locally demixes a temperature‐responsive solution to produce a single optothermal droplet. Spatial precision is assured by the well‐defined thermal field and temporal accuracy 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. Further, laser foci are programmed to orchestrate the liquid patterns in a time‐continuous manner to produce liquid animations on the microscale with high fidelity. While focused lasers are routinely used to manipulate solid particles or to microfabricate solid materials, the current strategy embraces the merits of liquids and features functional complexity in information encryption, payload transportation, and reaction localization. The strategy is further applicable in scenarios such as subcellular organization of biomolecular condensates and programmable modulation of non‐equilibrium systems.

Optical Manipulation of Soft Matter

“…This allowed for the production of programmable optothermal droplets with spatiotemporal addressability and enabled the creation of liquid painting and liquid animation with high fidelity (Figure 5a). [58] Lipids are a primary component of natural cell membranes and are also utilized in the construction of biomimetic cell membranes. [59] The direct manipulation of lipid membrane domains is achieved by the synergistic action of optical force and photothermal effects generated by the focused laser beam.…”

Engineering the Coacervate Microdroplet Interface via Polyelectrolyte and Surfactant Complexation

“…Over the past few decades, coacervates have been recognized as an emerging research area in various fields, such as origin of life, − membraneless cellular compartments, − bioreactors − and drug delivery. − Complex coacervate microdroplets are formed via spontaneous liquid–liquid phase separation by mixing two oppositely charged polyelectrolytes in water, resulting in a dense, polyelectrolyte-rich phase (the coacervate phase) dispersed in a dilute continuous phase . Due to their all-aqueous nature, these droplets have been described as water-in-water (w/w) emulsion systems, which are colloidal dispersions consisting of two immiscible aqueous phases and exhibit good biocompatibility and environmental friendliness. − However, due to their lack of a membrane, coacervate droplets typically lack selective permeability to solutes and are susceptible to coalescence and pH/salt-induced disassembly, which limits their applications.…”

Light‐Driven Spatiotemporal Pickering Emulsion Droplet Manipulation Enabled by Plasmonic Hybrid Microgels

“…Although plasmonic nanoparticles may function as light-to-heat converters under specific wavelengths, the fast and efficient light-mediated response of plasmonic nanoparticle-stabilized Pickering emulsions remains largely unexplored. [45,46] In addition, it is still challenging to initiate reactions or the interaction of Pickering emulsion droplets containing different reagents by droplet merging or directed inter-droplet transportation.…”