High-speed and drop-on-demand printing with a pulsed electrohydrodynamic jet

We present a pulsed dc voltage printing regime for high-speed, high-resolution and high-precision electrohydrodynamic jet (E-jet) printing. The voltage pulse peak induces a very fast E-jetting mode from the nozzle for a short duration, while a baseline dc voltage is picked to ensure that the meniscus is always deformed to nearly a conical shape but not in a jetting mode. The duration of the pulse determines the volume of the droplet and therefore the feature size on the substrate. The droplet deposition rate is controlled by the time interval between two successive pulses. Through a suitable choice of the pulse width and frequency, a jet-printing regime with a specified droplet size and droplet spacing can be created. Further, by properly coordinating the pulsing with positioning commands, high spatial resolution can also be achieved. We demonstrate high-speed printing capabilities at 1 kHz with drop-on-demand and registration capabilities with 3-5 mu m droplet size for an aqueous ink and 1-2 mu m for a photocurable polymer ink.