Division of Microelectronics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
Lab Chip. 2011 Jun 7;11(11):1879-85. doi: 10.1039/c0lc00661k. Epub 2011 Apr 12.
A method for on-demand droplet fusion in a microfluidic channel is presented using the flow created from a single explosively expanding cavitation bubble. We test the technique for water-in-oil droplets, which are produced using a T-junction design in a microfluidic chip. The cavitation bubble is created with a pulsed laser beam focused into one droplet. High-speed photography of the dynamics reveals that the droplet fusion can be induced within a few tens of microseconds and is caused by the rapid thinning of the continuous phase film separating the droplets. The cavitation bubble collapses and re-condenses into the droplet. Droplet fusion is demonstrated for static and moving droplets, and for droplets of equal and unequal sizes. Furthermore, we reveal the diffusion dominated mixing flow and the transport of a single encapsulated cell into a fused droplet. This laser-based droplet fusion technique may find applications in micro-droplet based chemical synthesis and bioassays.
提出了一种在微流道中按需融合液滴的方法，该方法利用单个爆炸式膨胀空化泡产生的流动来实现。我们针对油包水液滴进行了测试，这些液滴是使用微流控芯片中的 T 型接头设计产生的。通过将聚焦的脉冲激光束照射到单个液滴中产生空化泡。高速摄影技术揭示了液滴融合可以在几十微秒内被诱导，并且是由分离液滴的连续相膜迅速变薄引起的。空化泡崩溃并重新凝聚到液滴中。液滴融合在静态和运动的液滴以及大小相等和不相等的液滴中都得到了验证。此外，我们揭示了扩散主导的混合流以及单个包裹细胞向融合液滴的传输。这种基于激光的液滴融合技术可能在基于微液滴的化学合成和生物测定中得到应用。
