On-demand, parallel droplet merging method with non-contact droplet pairing in droplet-based microfluidics

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We demonstrate a simple approach for merging droplets in an on-demand, parallel manner via non-contact pairing of two droplets. The non-contact pairing can be achieved by exploiting flow-induced deformability of a droplet with a unique structure of merging element. Non-contact paired droplets, which are initially stabilized by surfactant molecules, can be merged simply by destabilizing the droplet interface and bringing two droplets into contact. On-demand, parallel droplet merging is performed with a proper pressure profile achieved by a pneumatic pressure supply system, and merging process is solely dependent on the pressure-driven fluid flow. We achieved an average merging efficiency of 90.0 % (SD = 3.14, n = 450) in performing parallel merging in a non-contact paired droplet array. We also evaluated the on-demand merging performance by measuring the average merging delay time (mean = 3.25 s, SD ± 1.09 s, n ~ 180). Furthermore, we demonstrated the applicability of our device for the initiation of a chemical reaction through the merging of two droplets with different chemical contents. We believe that the proposed method will be useful for studying various droplet-based reactions.

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This research was supported by BioNano Health-Guard Research Center funded by the Ministry of Science, ICT & Future Planning (MSIP) of Korea as Global Frontier Project (H-GUARD_2014M3A6B2060526) and Basic Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2012R1A1A2006305), and a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (Grant Number: HI15C0001).

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Correspondence to Joonwon Kim.

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Lee, S., Kim, H., Won, D. et al. On-demand, parallel droplet merging method with non-contact droplet pairing in droplet-based microfluidics. Microfluid Nanofluid 20, 1 (2016).

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  • Droplet-based microfluidics
  • Deformability
  • On-demand droplet merging
  • Laplace trap
  • Non-contact pairing