Particle image velocimetry for spray measurement of an Aerosol-on-Demand jet-printhead

Aerosol jet printing offers advantages over common inkjet methods for printed electronics, such as finer structures, layer homogeneity, and 3-D substrate printing capabilities. Our institute is developing a patented Aerosol-on-Demand (AoD) jet-printing process. Understanding the aerosol spray’s droplet velocity fields is crucial for this development. We report on the use of the particle image velocimetry method to measure the droplet velocities and to demonstrate the on-demand capability of the AoD printing principle. The nature of the spray with very high velocity gradients on the one hand, and sparse droplet density in some regions on the other hand poses great challenges for PIV resulting in vector replacement rates of approximately 45%. Despite this, the measurements successfully quantified the maximum droplet velocities in excess of 3 ms$^{-1}$ and demonstrated the on-demand capability, confirming a spray cessation time of approximately 50 ms.