10.1063/5.0075820.2

Abstract

Confined interface vibration inkjet printing (CIVIJP) in another immiscible liquid phase has been investigated previously as a novel strategy proposed for actively generating ultra-fine droplets, which can be dozens of times smaller than the orifice from which they are ejected. However, the working frequency of this novel CIVIJP technique is much lower than the traditional inkjet printing, and the unique droplet generation mechanism and the interface behavior of CIVIJP are still unapprehended at high working frequency. Here, the CIVIJP working at high frequency was explored to reveal the droplet generation mechanism and improve its printing efficiency. The subharmonic resonance and antiresonance effects which have a final influence on the interface behavior and size of the droplets were found in the case of high working frequency. The droplets' size will fluctuate regularly with the increasing printing frequency induced by the residual vibrations. The subharmonic resonance and antiresonance depend on whether the residual movement of the meniscus is in-phase or out-of-phase with the next droplet formation cycle. The mechanism of this phenomenon was delineated in detail, and the theoretical predicted optimal resonance frequencies were in good agreement with the experimental values. Based on the above mechanisms, a new route was proposed to regulate the size of the droplets facilely. The antiresonance effect was successfully utilized to develop an unprecedented droplet propelling regime after the droplet being dispensed with the same nozzle.