Drop‐on‐Demand Inkjet Printhead Performance Enhancement by Dynamic Lumped Element Modeling for Printable Electronics Fabrication

Abstract

The major challenge in printable electronics fabrication is the print resolution and accuracy. In this paper, the dynamic lumped element model (DLEM) is proposed to directly simulate an inkjet-printed nanosilver droplet formation process and used for predictively controlling jetting characteristics. The static lumped element model (LEM) previously developed by the authors is extended to dynamic model with time-varying equivalent circuits to characterize nonlinear behaviors of piezoelectric printhead. The model is then used to investigate how performance of the piezoelectric ceramic actuator influences jetting characteristics of nanosilver ink. Finally, the proposed DLEM is applied to predict the printing quality using nanosilver ink. Experimental results show that, compared to other analytic models, the proposed DLEM has a simpler structure with the sufficient simulation and prediction accuracy.

Modelling of Power-Law Fluid Flow Inside a Piezoelectric Inkjet Printhead

“…In the end, the quasi-one-dimensional equation for the power-law fluid flow in the inkjet tube is obtained. As the size of the piezoelectric printhead is small and the displacement of liquid inside the tube is relatively small, the radial displacement of the fluid in the tube is not taken into consideration and the body force and convective acceleration are negligible [ 20 ]. Therefore, the Navier-Stokes equation for describing the flow inside the printhead can be simplified as follows: where u is the axial velocity of the fluid, p is the pressure, and τ is the viscous stress while flowing.…”

“…The transmission of pressure waves inside the tube is transient enough to be assumed to be adiabatic. The liquid inside obeys the state equation [ 20 ]. Thus, (21) can be written as: where c 2 ρ 0 is the initial pressure inside the tube.…”

“…With the method of hydrodynamic model analysis, Lee et al [ 19 ] presented an optimization scheme including the frequency of the driving voltage, the properties of the ink, the surrounding temperature and the shape of the interface between the ink and the air. The dynamic lumped element model [ 20 ] was proposed to simulate and control the droplet formation process and proved to be simpler than other analytic models. The models in all of the aforementioned studies include a description of the fluid flowing inside the inkjet printhead, which could be the basis for designing the actuation control in a systematic way [ 21 ].…”

A Multi-Fidelity Model for Simulations and Sensitivity Analysis of Piezoelectric Inkjet Printheads

“…The LEM here describes the electro-mechanical domain as an equivalent electrical circuit with lumped parameters of analogous electrical components (resistors, capacitors, and inductors) to describe the electrical and mechanical properties. The equivalent circuit approach is further refined to include both domains to study the behaviour of inkjet printheads [ 9 , 10 , 11 ].…”

“…The accuracy of any equivalent circuit models depends on the evaluation of its lumped parameters for various elements in the circuit. In practice, simplification of physics and geometrical complexity is normally used to obtain lumped parameters [ 9 , 10 ]. This could lead to large errors and over-simplification when using the LEM approach for prediction of system performance.…”