Control of droplet formation by operating waveform for inks with various viscosities in piezoelectric inkjet printing

Inkjet printing has adopted several new materials as inks for the fabrication of devices. In order to improve the printability, the droplet formation behavior of inks with various physical properties must be determined. This study investigates the effect of viscosity on the droplet formation process with fluids with various Ohnesorge numbers. Strobe photography is employed to observe droplets ejected from the nozzle. Experimental results show that the driving waveform parameters can significantly alter jetting behavior, and one should not be considering the fluid properties only. In addition, the proper driving waveforms for inks with various viscosities in squeeze-mode piezoelectric inkjet printing are proposed.