Comparison of micro-dispensing performance between micro-valve and piezoelectric printhead

Abstract

In micro-dispensing applications, printhead activation mechanism, its design and operating parameters are integrated together to affect the droplet generation process. These factors give each printhead advantages and limitations over the others in specific fabrication. Hence, multiple printheads on micro level fabrication are preferred to perform multi-material dispensing task. In this paper, the mechanisms of two commonly used micro printheads, solenoid actuated micro-valve and piezoelectric printhead are discussed. Comprehensive experiments are conducted to characterize their performance and the results are analyzed so as to explore optimal droplet formation condition. With regards to the operational parameters' influence on droplet formation, micro-valve is investigated in terms of pressure, and operational on time, and piezoelectric printhead is investigated based on pulse amplitude, and width of driving pulse. Nozzle size, a key design parameter in the two printheads, is also studied according to its influence on dispensing capability. To facilitate dispenser selection, the two printheads are compared based on droplet size, droplet stability, droplet velocity, and dispensing viscosity of successful ejection. Other factors such as chemical compatibility, time consumption in determining optimal condition and reliability of dispensing process are also reported to play an essential role in this selection. Our investigation on the relationship between related parameters and dispensing performance will not only benefit dispenser selection in multi-material dispensing application, but also build a solid background to develop multiple printhead system for fabrication of bioengineering components.

Performance characterization of drop-on-demand micro-dispensing system with multi-printheads

“…According to our printhead characterization experiment, two driving pulse windows are observed in single drop generation (Sun et al 2009), a smaller pulse width range with low duty cycle (1st window) and a big pulse width range with high duty cycle (2nd window). The driving pulse from the 2nd window is used in our application, due to the associated stable droplet velocity.…”

“…These systems basically consist of two components: the multiple printheads with their associated drivers and the XYZ precision stage to move the printheads and substrate onto the desired position. The influence of printheads' operational parameters on printing performance has been extensively reported (Sun et al 2009;Tsai et al 2008). However, the factors such as printing parameters from the XYZ stage, fixture of printheads, stage configuration or other disturbance and vibration are not fully addressed yet.…”

Plug-in nanoliter pneumatic liquid dispenser with nozzle design flexibility

“…4,5 To dispense liquids in minute volumes, dispensers have been developed for use with different actuating methods such as thermal-bubble, piezoelectric, pneumatic, and solenoid actuation. [6][7][8][9][10] Although commercial dispensers have high reliability and accuracy, there is the inevitable issue of channel clogging induced as a result of the narrow liquid paths inside the dispenser and various liquid properties. 11,12 Therefore, frequent maintenance is required.…”

“…Specifically, clamping and thread-tightening have been chosen previously. [8][9][10] However, the reported integration procedures are cumbersome and time-consuming and hinder prompt operation. For this reason, the need for simplicity of integration has been increasing.…”

Velocity control of nanoliter droplets using a pneumatic dispensing system

“…In the most dispensing systems, a droplet's volume and velocity are both linearly dependent on the magnitude of the driving force or on the transferred kinetic energy [20][21][22][23]. Therefore, in conventional dispensing systems the droplet's velocity cannot be controlled without affecting its volume.…”