High‐throughput deterministic single‐cell encapsulation and droplet pairing, fusion, and shrinkage in a single microfluidic device

In this article, we present a microfluidic device capable of successive high‐yield single‐cell encapsulation in droplets, with additional droplet pairing, fusion, and shrinkage. Deterministic single‐cell encapsulation is realized using Dean‐coupled inertial ordering of cells in a Yin‐Yang‐shaped curved microchannel using a double T‐junction, with a frequency over 2000 Hz, followed by controlled droplet pairing with a 100% success rate. Subsequently, droplet fusion is realized using electrical actuation resulting in electro‐coalescence of two droplets, each containing a single HL60 cell, with 95% efficiency. Finally, volume reduction of the fused droplet up to 75% is achieved by a triple pitchfork structure. This droplet volume reduction is necessary to obtain close cell–cell membrane contact necessary for final cell electrofusion, leading to hybridoma formation, which is the ultimate aim of this research.