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Electrohydrodynamic (EHD) printing has emerged as a promising technique for high-resolution additive manufacturing, but the frequency limits and optimal operating ranges for drop-on-demand EHD printing remain elusive. This lack of clarity has significant implications for printing efficiency and accuracy. Here, we present a theoretical model based on the Lagrange equation to calculate the eigenfrequency in EHD printing. Our study elucidates the dynamic relationships between the eigenfrequency and key process parameters (e.g., voltage, meniscus diameter, and center angle), and reveals the intrinsic relationship between the jetting frequency and the oscillation eigenfrequency, demonstrating that the jetting frequency is limited by the eigenfrequency. This conclusion has significant implications for the design of high frequency EHD printing systems; it highlights opportunities to increase the eigenfrequency by optimizing parameters such as meniscus radius/center angle. In addition, it is interesting to note that the high-order-mode jetting phenomenon can be utilized to break through the traditional frequency limit of the low-order mode. This work can serve as an instructive benchmark of the EHD printing frequency, which provides a basis for designing a high-frequency EHD printing system. [ABSTRACT FROM AUTHOR]

Electrohydrodynamic (EHD) jetting is a promising technique with ultra-high resolution, broad compatibility with various inks, and tunable printing modes. However, it suffers from poor efficiency, which urgently calls for an addressable multi-nozzle printhead. Unlike traditional EHD printing which treats the liquid inside the printhead as an equal potential body, this work has proposed to realize addressable jetting by tuning the potential drop between the non-triggered nozzles (connected to a resistor and then grounded) and the triggered nozzles (connected to a high-voltage) through voltage division principle. We present an equivalent circuit model to predict the potential drop within the printhead, which largely depends on the liquid conductivity, channel character, and external auxiliary resistors, and these results match well with experiments and simulations. Besides, we further investigate the jet deflection behavior of the printhead, finding that 1.5 < H / d n < 3 (the ratio of printing height to the nozzle diameter) and 0.6 < k < 0.8 (the ratio of the non-triggered nozzles to the triggered nozzles) are preferred working area for addressable and precise EHD printing. This addressable design does not need a complex extractor underneath the nozzle, which is promising for future high-density and large-scale EHD printheads. [ABSTRACT FROM AUTHOR]

We investigate multi-mode oscillation and ejection behavior in pulsed electrohydrodynamic (EHD) printing in this paper. The results show that multi-mode oscillation is determined by the damping ratio of the meniscus, while the phase difference between meniscus oscillation and the electric field governs whether jetting can occur. High-order-mode jetting can occur around the corresponding resonant frequency of a low damping ratio system. This enhances the frequency limit to approximately 2.62 times that of traditional pulsed EHD printing, providing an efficient approach to high-frequency EHD printing. [ABSTRACT FROM AUTHOR]