Interfacial Tension Modulates Viscous Microfluidic Droplet Generation.

Mammalian cell culture in nanoliter droplets of extracellular matrix has recently attracted interest as a platform for high throughput drug screening on 3D tissue models. Microfluidic droplet generation using basement membrane extract, such as Matrigel or Cultrex, is complicated by the fact that the viscosity is orders of magnitude higher than that of water. Consequently, conditions that produce quality water droplet generation can fail with basement membrane extract due to the higher capillary number. Here, a parametric study using a T-junction device demonstrates that higher viscosity can be abrogated by lower interfacial tension, which is modulated by surfactant concentration.