Application Cases

Experiment Name: Electrohydrodynamic Jet Printing Experimental Observation Platform

Test Equipment: ATA-7030 high-voltage amplifier, function generator, oscilloscope, high-speed camera, laser light source controller, laser light source, computer, etc.

Experimental Procedure:

Figure 1: Cone-Jet Observation Platform: (a) Experimental Setup and (b) Main Experimental Equipment.

1. High-speed camera

2. Microscopic lens

3. Micro-syringe pump

4. Syringe pump controller

5. Laser light source controller

6. Laser light source

7. High-voltage amplifier

8. Function generator

9. Oscilloscope

10. XY mobile platform

11. Computer control system
    Components 1, 2, 5, and 6 form the high-speed camera observation system, while components 7, 8, and 9 form the high-voltage generation system.

The electrohydrodynamic jet printing experimental platform is shown in Figure 1(a). Its main functional modules include the high-voltage generation system, high-speed camera observation system, flow drive system, and platform motion control system. During the experiment, the ink is injected through a syringe fixed to the actuator and driven by a micro-pump, as shown in Figure 1(b) as component 3. The injection speed can be adjusted by setting the flow rate via the micro-pump controller, with a minimum flow rate of 138 nL/min. The syringe can be easily fitted with 20–30G stainless steel needles, connected to the positive terminal of the high-voltage amplifier via alligator clips. The high-voltage system consists of the high-voltage amplifier, function generator, and oscilloscope, as shown in components 7, 8, and 9 in Figure 1(b). The function generator produces arbitrary waveform signals, which are input into the high-voltage amplifier for voltage amplification without frequency amplification. The function generator can generate AC pulses with a maximum frequency of 25 MHz, while the high-voltage amplifier can amplify voltages up to ±3 kV without distortion. The amplified voltage is measured by the oscilloscope, which displays 1/1000 of the input voltage. All three instruments in the high-voltage system can be connected to a computer and controlled via a unified LabVIEW-based software interface.

The syringe and actuator are fixed on two parallel FSL40 linear guide screw sliding modules, which can move vertically at a minimum speed of 1 mm/s, corresponding to the Z-axis lifting platform in Figure 1(a). Directly below the syringe is the resin substrate, on which a smooth stainless steel sheet is placed. The stainless steel sheet is connected to the negative terminal of the high-voltage amplifier via alligator clips. Transparent insulating tape is applied to the stainless steel sheet to prevent contact between the positive and negative electrodes during the experiment. The substrate is positioned on an X-Y mobile platform composed of two vertically arranged No. 28 micro-stepper motors, powered by a 24V switching power supply. The motor control terminals are connected to the computer, and the operating speed can be set via software developed using the Microsoft Foundation Class Library, with a minimum speed of 25 μm/s.

The high-speed camera observation system is positioned horizontally at the syringe needle tip, consisting of components 1, 2, and 4 in Figure 1(b). The high-speed camera captures images at 2 million pixels, with a maximum frame rate of 3000 fps in full-frame mode. The microscopic lens magnifies the image up to 4×. The laser light source provides high-intensity illumination, ensuring sufficient brightness even at 10,000 fps in small-frame mode.

Experimental Results:

Figure 2: Jet Breakup Observation Platform: (a) Main Experimental Equipment and (b) Needle-Cylinder Coaxial Electrode Structure.

1. Flow drive system

2. High-voltage system

3. High-speed camera

4. Cylindrical electrode

5. LED light source

6. Computer

7. Waste liquid receiver
   Red and black solid lines represent positive and negative electrode connections, respectively, while green dashed lines indicate connections to the computer.

To observe the jet breakup process, Figure 2 shows the experimental setup for coaxial charged jets. In typical electrohydrodynamic jet printing experiments, the diameter of the cone-jet region is much smaller than the nozzle inner diameter. For a 27G needle, the jet diameter does not exceed 10 μm, making it impossible to capture such fine jet interface changes even with the most advanced high-speed cameras. Therefore, the coaxial charged jet device shown below generates jets directly extruded from the needle without forming a Taylor cone, with a jet radius of approximately 100 μm. The jet is surrounded by a transparent conductive electrode to generate a radial electric field, as shown in component 4 of Figure 2(a). In the jet breakup experiment, relevant dimensionless parameters are kept close to those in electrohydrodynamic jet printing, similar to the similarity principle in wind tunnel experiments. The experimental setup mainly includes the electro-jet generation module and the high-speed camera observation module. In the electro-jet generation module, the jet is driven by a syringe pump, ejected through the needle electrode, and passes through the coaxial electrode. This module is also known as the needle-cylinder electrode structure. The needle electrode is supplied with DC voltage, while the coaxial electrode is grounded. The droplets formed after jet breakup are collected by a receiver. The high-speed camera captures the breakup process with a maximum frame rate of 2×10⁴ fps, enabling the observation of interface characteristics near the breakup moment.

High-Voltage Amplifier Recommendation: ATA-7030

Figure: ATA-7030 High-Voltage Amplifier Specifications

The experimental materials in this article were compiled and published by Xi'an Aigtek Electronics. For more experimental solutions, please continue to follow the Aigtek official website.