In this paper, we demonstrate the incorporation of dye-based liquid lasers within or around flowing aqueous microfluidic droplets. In particular, we use dye solutions in benzyl alcohol, and either disperse an ensemble of small (∼20 μm) lasing droplets within large (∼500 μm) aqueous droplets flowing in a simple glass capillary-based microfluidic device, or ‘wrap’ a thin (∼10 μm) lasing benzyl alcohol shell around larger (∼560 μm) microfluidic aqueous droplets. We experimentally and theoretically characterize the lasing behavior in both cases, which is supported by whispering-gallery mode (WGM) optical resonances at the droplet interfaces. We showcase a simple application of our method, which highlights the advantages of having embedded, spatially segregated laser sources within a droplet containing a model analyte solution. With this method, each microfluidic droplet now functions not only as an isolated experiment flask, but is also capable of on drop sensing that exploits WGM-based lasing, thus expanding the possibilities for online monitoring of biophysical/biochemical processes and sensitive detection of biomolecules in droplet-based microfluidics.

中文翻译：

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在液态微流体液滴内部或周围嵌入液体激光器†

在本文中，我们演示了在流动的水性微流体液滴内部或周围引入基于染料的液体激光器。特别是，我们使用在苄醇中的染料溶液，或者将一组小的（〜20μm）激光液滴分散在一个简单的基于玻璃毛细管的微流控设备中流动的大的（〜500μm）水性液滴中，或者将其“包裹”起来。薄的（〜10μm）激光苄醇壳围绕较大（〜560μm）的微流水性液滴。我们在实验和理论上都描述了这两种情况下的激光行为，这由液滴界面处的耳语画廊模式（WGM）光学共振支持。我们展示了我们方法的一个简单应用，该方法突出了在包含模型分析物溶液的液滴内嵌入空间上隔离的激光源的优势。用这种方法