Influence of ink properties and voltage parameters on piezoelectric inkjet droplet formation

For piezoelectric inkjet printing, it is important to stably eject droplets and to accurately control their size and velocity. This paper aims to study the effects of ink properties and voltage parameters on the formation of piezoelectric inkjet droplets. A high-speed camera was used to watch the process of droplet formation for sodium alginate, alcohol, and gelatin inks with Z values between 2.1 and 16.2, at 50 V–120 V voltage amplitude and 2000 Hz–10000 Hz ejecting frequency. The images of droplet formation show that as the ink concentration increases, the ink jettability is reduced, the velocity of the droplets decreases significantly, and their diameter decreases slightly. As the voltage amplitude increases, the ink jettability improves, the velocity of the droplets increases significantly, and their diameter increases slightly. The voltage frequency has no obvious effect on both velocity and diameter of the ink droplet. However, when the voltage frequency is 8000 Hz or above, it may cause the continuous ejection of droplets to coalesce. Our findings may support the efforts to achieve improved stable ejection of droplets and to better control their size and velocity.