Simulation and experiment on droplet dispensing for a valve-controlled pneumatic jetting system

Abstract

Valve-controlled pneumatic jetting technology, which is characterized by high accuracy, fast dispensing speed, and strong adaptability, has been widely applied in the field of life sciences. This paper examines the formation and separation of droplets by reporting the comprehensive influence of system parameters on the morphological changes of droplets, which was simulated by using several dimensionless numbers, including the Weber number, Reynolds number, and Ohnesorge number. In the next step, the simulation results are verified through experimental results, and the rules of the regular ejection of droplets are summarized. The simulation and experimental results indicate that if We is higher than the upper critical value or lower than the lower critical value, jetting failure situations, such as adhesion, satellite droplets, sputtering, and flow-stream will occur. Similarly, jetting failures such as adhesion or flow-stream will appear with oversize or undersize Reynolds number. Through Oh, only when the system parameters should be adjusted to keep the values of We and Re within the proposed range can normal droplets be jetted. The research also provides the recommended ranges of system parameters for ensuring successful droplet ejection, which has important reference significance for guiding the design and control of valve-controlled pneumatic jetting systems.