Application Cases

Experiment Name: Droplet Microfluidics Experiment

Research Direction: Droplet Microfluidics

Experimental Content:
This experiment uses a signal generator to produce a sinusoidal signal, which is amplified by the ATA-2161 high-voltage amplifier. The amplified high-voltage signal is applied to the electrodes of the microfluidic chip, generating a non-uniform electric field to charge droplets passing through the region. By adjusting the frequency and amplitude of the signal, the charge of the droplets is precisely controlled, enabling accurate manipulation of charged droplets.

Testing Equipment:
Signal generator, oscilloscope, ATA-2161 high-voltage amplifier, microfluidic chip, etc.

Experimental Procedure:

Figure: Schematic Diagram of the Experimental Setup

The experimental procedure begins with preparation, including checking and connecting the signal generator, ATA-2161 high-voltage amplifier, and microfluidic chip, preparing continuous and dispersed phase fluids, setting up the syringe pump, and connecting microfluidic tubing. All electrical connections are carefully inspected for insulation and safety.

Next, the system is debugged: the signal generator is started with initial sinusoidal signal parameters, the ATA-2161 amplifier is activated with appropriate gain settings, and the amplified signal waveform is monitored using an oscilloscope to ensure stability and minimal distortion.

Once the system is stable, the droplet generation and charging experiment begins. The syringe pump is started to adjust the flow rate ratio of the continuous and dispersed phases, and the frequency and size of droplet generation are observed and optimized. The high-voltage signal is applied to charge droplets passing through the electrode region, and their motion in the electric field is observed under a microscope.

For parameter testing, the signal frequency is gradually varied, and the voltage amplitude is adjusted at each frequency. The motion trajectories of droplets under different parameter combinations are recorded, and high-speed imaging captures the droplet movements.

Experimental Results:

Figure: Experimental Results of Droplet Microfluidics

To validate the potential of the voltage amplifier in droplet sorting, a symmetric electric field environment (±300 V) was used. By controlling the charging voltage (original signal ±0.5 V, amplified to ±50 V by the voltage amplifier) and charging time (T+c and T-c), droplet charging was achieved. The microscopic charge properties of the droplets were transformed into macroscopically observable motion trajectories, indirectly characterizing the charged state, as shown in Figure 4.41.

In the experiment, without the voltage amplifier, droplets showed no deflection. With the voltage amplifier, charged droplets exhibited stable deflection. T-c was maintained at one droplet generation cycle (TD), while T+c was gradually increased from TD to 7×TD. The results showed that uncharged droplets (Vc=0 V) moved in a straight line. As T+c increased, the number of positively charged droplets (red) increased correspondingly, while the number of negatively charged droplets (green) remained unchanged. The number of positively charged droplets per cycle precisely matched the ratio T+c/(n×TD) (e.g., with T+c=3×TD, three positively charged droplets and one negatively charged droplet were generated per cycle), and the pattern was highly reproducible.

This precise droplet counting and charging time matching demonstrate the controllable and reproducible charging capability of the system using the ATA-2161 high-voltage amplifier, laying the foundation for charge-based droplet sorting technology.

Recommended Power Amplifier: ATA-2161 High-Voltage Amplifier

Figure: ATA-2161 High-Voltage Amplifier Specifications and Parameters