Laser‐Induced Nanodroplet Injection and Reconfigurable Double Emulsions with Designed Inner Structures

• Published in: Advanced science 2019-09, Vol.6 (17), p.1900785-n/a
• Main Authors: Guo, Jin‐Kun, Hong, Seung‐Ho, Yoon, Hyun‐Jin, Babakhanova, Greta, Lavrentovich, Oleg D., Song, Jang‐Kun
• Format: Article
• Language: English
• Subjects: Chemistry; Communication; Communications; Design; double emulsions; ENGINEERING; laser injecting; Lasers; liquid crystal droplets; marangoni effect; Materials Science; Microscopy; Phase transitions; Point defects; Science & Technology - Other Topics; Surfactants; whispering gallery mode
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.201900785

Microfabrication of complex double emulsion droplets with controlled substructures, which resemble biological cells, is an important but a highly challenging subject. Here, a new approach is proposed based on laser‐induced injection of water nanodroplets into a liquid crystal (LC) drop. In contrast to the conventional top‐down microfluidic fabrication, this method employs a series of bottom‐up strategies such as nanodroplet injection, spontaneous and assisted coalescence, elastically driven actuation, and self‐assembly. Each step is controlled precisely by adjusting the laser beam, interfacial tension, and its gradients, surface anchoring, and elasticity of the LC. Whispering gallery mode illumination is used to monitor the injection of droplets. A broad spectrum of double emulsions with a predesigned hierarchical architecture is fabricated and reconfigured by temperature, laser‐induced coalescence, and injection. The proposed bottom‐up method to produce customized microemulsions that are responsive to environmental cues can be used in the development of drug delivery systems, biosensors, and functional soft matter microstructures. Laser beam exposure of the liquid crystal (LC)–water interface injects nanodroplets of water into the LC drop. Droplets grow and interact through the elastic environment of the LC and self‐assemble into complex hierarchical architectures that can be designed and reconfigured. The proposed bottom‐up technique represents a precise and multifunctional tool in microfabrication of liquid and soft matter.