Application Cases

Experiment Name: Research and Application of Low-Cost Digital Microfluidic Chips Based on Electrowetting

Experiment Purpose: To build the hardware setup of a digital microfluidic system, select the power supply and circuit control devices, and then fabricate two types of low-cost DMF chips with different electrode materials: one based on ITO metal electrodes made on a PET substrate using laser etching technology, and the other with carbon ink electrodes made on a polyester film and non-woven fabric substrate using screen printing technology. The hardware setup combined with the DMF chips constitutes a digital microfluidic system, which is used to demonstrate the feasibility of droplet movement and merging on the chip, and finally to analyze the forces acting on the moving droplets.

Testing Equipment: ATA-2161 high-voltage amplifier, function signal generator, relay, oscilloscope, microcontroller, etc.

Experiment Process:

Figure 1: Diagram of the Digital Microfluidic System

The digital microfluidic system consists of three parts: power supply device, circuit control device, and the digital microfluidic chip. The design and construction of the digital microfluidic system involve connecting these three parts and precisely controlling the on-off of the AC electrical signals delivered to the chip electrodes to drive the droplets on the chip, as shown in Figure 1.

According to the principle of electrowetting, applying a high voltage to the electrodes on the chip can induce an interfacial tension gradient within the droplet, causing the hydrophobically treated droplet to move. The on-off of the AC electrical signals delivered to the chip electrodes is controlled by the timing sequence input from the microcontroller. The output AC voltage, amplified by the function generator and the high-voltage amplifier, is 300Vrms with a frequency of 1kHz.

Experimental Results:

The droplet selected for the experiment is an 8μL deionized water solution. Under the condition of an input AC voltage of 300Vrms and a sine wave frequency of 1kHz, the electrode on-off time is set to 2s via the timing sequence, meaning it takes 2s for the droplet to move to the next position on the chip. As shown in Figure 2, the digital microfluidic chip successfully achieved droplet movement and merging.

Figure 2: Droplet Movement

High-Voltage Amplifier Recommendation: ATA-2161

Figure: Specification Parameters of the ATA-2161 High-Voltage Amplifier

Applications: Ultrasonic testing, non-destructive testing, driving piezoelectric ceramics, dielectrophoretic cell sorting, ultrasonic atomization, ultrasonic focusing

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