Application Cases

Experiment Name: Control of Multiphase Oil-Based Droplet Behavior in AC Electric Fields

Experiment Content:
The study of oil-oil systems complements commonly used aqueous systems and is applicable to many scenarios incompatible with water or aqueous solutions. This includes extensive research in drug preparation, coating and composite material production, energy harvesting and management, and more. This experiment investigates different oil-based droplet systems classified by functional groups, such as alkyl, hydrocarbon, hydroxyl, and ester groups. Under coupled electrical and flow conditions, five typical droplet behaviors are defined: "no effect," "movement," "deformation," "interface rupture," and "chaos." A new dimensionless criterion is proposed for these behaviors in coupled flow-electric fields.

Research Direction: Droplet Behavior Control

Test Equipment: ATA-7030 high-voltage amplifier, signal generator, high-speed camera, microscope, syringe pump, etc.

Figure 1: Experimental Framework Diagram

Experimental Process:
In the experiment on controlling multiphase oil-based droplet behavior using AC electric fields, the high-voltage amplifier is a key device. Researchers use microfluidic chips to generate oil-based droplets. When the droplets reach the electric field control region, an AC electric field is applied via the high-voltage amplifier (ATA-7030). The high-voltage amplifier provides sufficient potential difference to induce droplet behaviors such as movement, deformation, splitting, and fusion under the influence of the electric field. By adjusting amplifier parameters like voltage and frequency, the trajectory and speed of the droplets can be precisely controlled. Researchers can observe the forces acting on the droplets in the electric field and study their deformation and motion behaviors influenced by the field. The high-voltage amplifier plays a crucial role in regulating and controlling the electric field strength, providing a controllable platform for researchers to gain deeper insights into the mechanisms of oil-based droplet behavior control in electric fields.

Experimental Results:

Figure 2: Experimental Results

1. In the SO/HDDA (alkyl)/MO/HDDA (hydrocarbon) systems, the product of the electrical Weber number and capillary number determines droplet behavior.

2. The dimensionless parameter d1/Wc, representing channel geometric constraints, has a significant impact in most droplet system studies.

3. Compared to aqueous droplet systems, oil-based droplets exhibit a reduced Maxwell-Wagner relaxation frequency. According to the equivalent circuit model, low frequencies reduce droplet voltage division, resulting in a distinct effective frequency range for oil-based droplets.

4. Increased droplet viscosity enhances shear forces in the flow, leading to droplet deformation and promoting state transitions.

5. The EG/HDDA (hydroxyl) system exhibits higher dielectric constant and conductivity, demonstrating controllable droplet fusion. Increased conductivity shifts the mechanism of AC electric field effects from direct field action on droplets to mutual attraction of polarized surface charges on droplets.

Recommended High-Voltage Amplifier: ATA-7030

Figure: ATA-7030 High-Voltage Amplifier Specifications

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