Hydrodynamic responses of a piezoelectric driven MEMS inkjet print-head

A high nozzle density, piezoelectric (PZT) driven inkjet print-head has been fabricated on silicon wafers using MEMS manufacturing process by our research team. To understand the performance of the print-head, numerical simulations and lumped element modeling (LEM) were conducted and the results show that the Helmholtz mode is the dominant resonance mode acting on the flow oscillations at the nozzle. The deflection of the thin piezoelectric membrane on the top of the narrow pressure chamber indicates that the actual speed of sound is slower than the intrinsic speed of sound in the fluid. The dynamic responses and also the magnitude of pressure rise at the pressure camber are affected by the ink's effective speed of sound. The results of LEM show that the hydraulic cross-talk through the common ink supply flow channel has an effect on the drop velocity when neighboring nozzles are fired simultaneously. The back flow through the restrictor results in the instantaneous pressure rise in the common ink supply channel that leads to the increases in the drop velocity. It shows that increasing the compliance in the common in supply channel is most effective to reduce the hydraulic crosstalk.