Application Cases

Experiment Name: Design and Implementation of an EHD Microdroplet Printing System

Test Equipment: High-voltage amplifier, function generator, probe, microscopic camera, computer, etc.

Experimental Procedure:

Figure 1: Overall Framework of the EHD Printing System

Figure 2: Schematic Diagram of the System Hardware Setup

The overall architecture of the designed system is shown in Figure 1, and Figure 2 illustrates the hardware configuration of the EHD microdroplet printing system. It primarily consists of a high-voltage pulse signal generation module, a liquid supply module, an imaging module, and a position control module. The printing nozzle, tubing, micro-syringe, and micro-syringe pump collectively form the liquid supply module. The high-voltage amplifier amplifies the voltage signal from the function generator and applies it to the substrate electrode plate and printing nozzle, constituting the high-voltage signal generation module. A long-focal-length microscope is connected to a high-speed camera, and the camera communicates with the computer to form the imaging module, enabling real-time monitoring of the printing process. The substrate sample to be printed is placed on the electrode plate, which is fixed on a translation stage. The three-dimensional movement of the translation stage enables high-precision positioning and alignment of the substrate, constituting the position alignment module. The computer is connected to the high-speed camera, bidirectional micro-precision syringe pump, three-coordinate displacement device, and function generator via USB electronic communication interfaces, allowing programmable control of each instrument through the computer.

High-Voltage Pulse Signal Generation Module:
The function generator in the high-voltage module must be capable of producing various waveforms, such as square waves and pulses, for printing. The maximum voltage generated by the function generator is 5 V, requiring the use of a high-voltage amplifier to amplify the output signal by a factor of 1000, producing kilovolt-level voltages. Since experiments in high-voltage environments are hazardous, the output current should be controlled within the milliampere range. The high-voltage amplifier achieves a maximum voltage amplification factor of 1000 times, operates at a frequency of 1 kHz, and provides an output current of 6 mA.

Experimental Results:
Based on the printing requirements of micro-hotplates, the hardware and software systems for EHD printing were designed and constructed. Instruments meeting the parameter standards were selected to build the voltage module, liquid supply module, imaging module, and position control module. USB interfaces were used to enable communication between the instruments and the computer, allowing the computer to control the voltage module, liquid supply module, imaging module, and position control module.

For the software component, a human-machine interactive interface was developed using LabVIEW to enable real-time observation of the printing process and results. This interface allows simultaneous control of multiple signal generators, the micro-precision syringe pump, and the three-coordinate translation stage, as well as one-click printing recognition. Additionally, the software incorporates an image recognition and automatic alignment module developed in MATLAB. The program coordinates the operation of various instruments, automatically recognizes the patterns and positions of micro-hotplates, moves them, and performs printing, thereby enhancing the system's automation level. Through the human-machine interface, both the printing nozzle and the micro-hotplate patterns on the substrate can be observed simultaneously. While recognizing and printing the micro-hotplates, the ink discharge from the printing nozzle can be monitored in real-time. In case of issues such as ink leakage or insufficient ink at the nozzle tip, the liquid level at the nozzle can be adjusted promptly, preventing printing defects and improving efficiency and yield.

Recommended High-Voltage Amplifier: ATA-7050

Figure: ATA-7050 High-Voltage Amplifier Specifications

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