In-Flight Imaging of Aerosol Jet Printer Droplets to Enable Spatially Resolved Flow Rate Measurements

Abstract

The effect of process drift in aerosol jet printing has been a hindering factor in its large-scale adoption in printed electronics. In this study, we developed an in-situ droplet imaging system using a double-pulse laser to quantify the distribution and velocity of sparse droplets between the aerosol jet printer nozzle and the substrate. The droplet velocity and distribution were then used to evaluate a spatially resolved droplet flow rate that was capable of detecting and quantifying process drift over time. Using the droplet imaging system, the effect of different focus ratios was analyzed. The droplet flow rate was shown to be indicative of the deposited line morphology for low to moderate focus ratios. At a high focus ratio, the tool was able to identify non-idealities in the fluid properties which are explained in a detailed analysis. Aerosol jet printing demonstrates significant promise for the additive manufacturing of electronics, and this work represents a step towards non-invasive, in-flight monitoring in real-time.