In droplet-based microfluidics, it is often necessary an external energy to control internal flows or mix samples, e.g. acoustic, electric, and magnetic fields. In this study, we introduce and explore vapor-driven solutal Marangoni flows that are appl...
In droplet-based microfluidics, it is often necessary an external energy to control internal flows or mix samples, e.g. acoustic, electric, and magnetic fields. In this study, we introduce and explore vapor-driven solutal Marangoni flows that are applicable to enhance the mixing efficiency and control the flow in a small volume by simply placing volatile liquid sources next to the sample. The internal flow patterns of the sample droplet are determined the location and the total number of the volatile sources. The flow patterns are measured using particle image velocimetry. We show that using this method the internal flows can be successfully controlled without any active control device, which can be also used as a mixer for the real microfluidics application in the near future.