Application Cases

Experiment Name: Experimental Testing of Capillary Infiltration Process

Test Purpose: This chapter designs and constructs an electrohydrodynamic jet printing experimental system to conduct printing tests on the prepared silicon tip printheads. The printing system mainly includes a gantry-type multi-dimensional servo motion platform, a high-voltage signal generation device, a visual imaging system, an injection and pipeline system, and the silicon tip printheads. Based on the constructed experimental system, different printing solutions were prepared, and experimental tests were carried out on the designed and fabricated silicon tip printheads.

Capillary infiltration provides the ink supply for the entire printing process. Effective capillary infiltration ensures the continuity of the printing process; therefore, investigating the capillary infiltration effect is crucial.

Test Equipment: High-voltage amplifier, Signal generator, Micro-injection pump, Silicon nano-tips, etc.

Experimental Process:

Figure 1: Flowchart of the electrohydrodynamic jet printing process

The main components of the precision three-dimensional printing platform system are: an XYZ three-dimensional motion system, a high-voltage signal generation device, a visual imaging system, an injection and pipeline system, and the silicon tip printheads. The flowchart of the electrohydrodynamic jet printing process is shown in Figure 1. The printing ink is supplied by a precision micro-injection pump, with a minimum feed rate of 0.764 nL/min. The printing substrate is a double-polished single-crystal silicon wafer with a thickness of 220 µm, cleaned using standard MEMS cleaning processes, and fixed onto the receiving flange using conductive adhesive tape. The receiving flange performs reciprocating motion via an X-Y axis micro-motion stage, with a maximum travel of 100 mm and a repetitive positioning accuracy of 1 µm, effectively ensuring the accuracy of the printed pattern. The motion control of the platform is managed by a control cabinet, and different motion trajectories can be achieved by inputting logical code. The tip printhead and the receiving substrate are connected to the positive and negative pulse high-voltage electrodes, respectively. The pulsed high voltage is generated through the coordinated control of a signal generator and a high-voltage amplifier.

In the experiment, a 4 wt% PEO aqueous solution was used as the test solution to examine the entire capillary infiltration process of the fabricated silicon tip printheads. As shown in Figure 2, initially, the PEO solution is delivered into the silicon cup ink reservoir by the precision micro-injection pump at a flow rate of 0.764 nL/min. Subsequently, the PEO solution, driven by capillary action, climbs along the sidewall of the silicon tip towards the apex, overcoming its own viscous force, surface tension, and gravity, as shown in Figure 2(b). Finally, the liquid film at the silicon tip apex stabilizes under the combined effects of capillary force, surface tension, viscous force, and gravity, as shown in Figure 2(c).

Figure 2: Diagrams of the capillary infiltration experiment (a) Initial state (b) Capillary infiltration process (c) Liquid film stabilization stage

Experimental Results:

First, based on the principles of electrohydrodynamic jet printing, a precision three-dimensional printing platform system was constructed. Then, using this system, the capillary infiltration test of the silicon tip printheads was completed. The results indicate that the silicon tips, after UV-ozone surface modification, exhibit excellent infiltration performance. This capability supplies ink for the subsequent printing process and ensures its continuity.

High-Voltage Amplifier Recommendation: ATA-7020

Figure: ATA-7020 High-Voltage Amplifier Specifications

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