Coaxial Electrospray Emitter Arrays


Core-shell micro encapsulations are useful for various applications including drug delivery, self-healing composites, and food processed lipophilic compounds.

Problem Addressed

Core-shell microencapsulation is required for several commercial applications like drug delivery or food processing. Generating near-monodisperse compound particles is essential to attain high efficiency. Current microencapsulation approaches produce particles in great quantities without acceptable control of the size spread or nominal size and viable encapsulation materials are limited. Coaxial electrospray generates precise particle sizes but its inherent low throughput is not commercially sustainable. However, an array of high-density electrospray emitters can greatly increase the throughput without sacrificing size spread. 3D printing makes it possible to create complex multiplexed coaxial electrospray sources at a very low cost.


Coaxial electrospray is an electrohydrodynamic process that creates core-shell microparticles by atomizing a coaxial electrified jet composed of two immiscible fluids. In the electrospray phenomenon, a high electrostatic field acting on the free surface of a liquid triggers an instability that transforms the meniscus into a conical shape. This cone balances the capillary forces and electrostatic pressure, forming droplets of an inner and outer liquid when operated in the electrospray cone-jet mode. Shell thickness and outer diameter of the core-shell particles can be modulated via the flow rates and diameters of the jet. Immiscible compound liquid droplets with a shell of photosensitive material are solidified using light. High resolution stereolithography can be used to manufacture freeform microfluidics at a small fraction of the cost per device, infrastructure cost, and fabrication time of a typical silicon-based microfluidic system.


  • Higher encapsulation efficiency
  • Uniform size distribution
  • 3D printing solidification reduces cost per device, infrastructure cost, and fabrication time