Analysis of drop-on-demand piezo inkjet performance

Abstract

For a particular printing ink and drop-on-demand piezoelectric inkjet printhead, piezoelectric voltage and temperature of the ink were varied to change the inkjet performance, and the jetting velocity of the inkjet was analyzed under various conditions. The ink was cooled by using a Peltier module, which was attached to the nozzle plate as a heat sink. The inkjet drops were captured by the shadowgraphic method using a high-speed camera. The positions and velocities of these drops were then estimated after image processing. The drop state was distinguished by dimensionless numbers, such as the Weber and Z numbers, to decide whether it was stable for ejection and printing. Increasing the piezoelectric voltage increased the ejection velocity but with an associated generation of satellite drops. Cooling the ink increased the viscosity, which in turn decreased the drop velocity while diminishing the satellite drops. Therefore, it was shown that the cooled ink enabled stabilized inkjet ejection.

Natural Polymers and Their Processing: Bottlenecks to Overcome Their Limitations in Medical Applications

“…Kang et al investigated piezoelectric voltage and temperature during printing and their results showed that increasing the piezoelectric voltage increased the ejection velocity of bioink but also had a generation of satellite drops (unintentional produced drops that are not placed where they were supposed to be placed). Lower temperatures decreased the number of satellite drops [33].…”

Recent advances in inkjet-printing technologies for flexible/wearable electronics

“…The shape of the piezoelectric transducer changes in response to an applied voltage, which generates a pressure pulse to the ink chamber simultaneously, causing droplets to be ejected drop by drop from the nozzle to the desired position. 48 As shown in Fig. 3b, piezoelectric inkjet printing can be divided into squeezing, pushing, shearing, or bending modes.…”

“…However, when the voltage frequency was 8 kHz or above, continuous ejection of droplets may coalesce and the printing results were affected. Moreover, Kang et al 48 studied the inkjet performance through piezoelectric voltage and ink temperature. It was found that the cooled ink increased the viscosity and decreased the inkjet velocity, obviously, thereby reducing the satellite-liked droplets.…”

Material assembly by droplet drying: From mechanics theories to applications

“…Organic and volatile solvents can also be used to control the ink's properties, including viscosity, surface tension, stability, particle size, density, contact angle, leveling performance, and evaporation rate. 147,148 Advanced droplet ejection technologies like thermal inkjet, 149 piezoelectric inkjet, 150 and electrohydrodynamic printing 151 enable ink droplets to land on the substrate with high precision and accuracy, resulting in sharp and crisp prints. 152,153 Finally, controlling the environment in which inkjet printing takes place, such as using heated platens or drying chambers, is crucial for optimal drying times and producing high-quality prints.…”