A geometrical model of pinch-off in digital microfluidics underpins "one-to-three" droplet generation

Abstract

Droplet generation is a fundamental sample handling procedure in digital microfluidics. In this work, a symmetric "one-to-three"droplet generation strategy is reported. A triangular model based on the geometrical relationship of reservoir droplets, sub-droplets, and liquid necks is proposed. Numerical investigation and corresponding experiments are performed. The results indicate that the proposed strategy produces a greater pressure difference for sub-droplet generation, especially when traditional droplet splitting is not possible with restricted microfluidics device geometries. The proposed geometrical model is a powerful tool to propose several improved droplet generation strategies. The "one-to-three"droplet generation strategy shows potential in practical applications and further studies for digital microfluidics platform.