Why Equip an Electrospinning System with Negative High Voltage? A New Study Provides an Answer

When selecting an electrospinning system, many researchers notice an important difference in high-voltage configuration.

Some systems use only a positive high-voltage power supply: the spinneret is connected to positive high voltage, while the collector is grounded. Other systems are equipped with both positive and negative high-voltage power supplies: the spinneret is connected to positive high voltage, and the collector can be connected to negative high voltage.

So what exactly does the additional negative high-voltage supply do?

Is it simply used to obtain a higher voltage, or does it have a deeper influence on the electrospinning jet and fiber deposition?

A 2026 study published in Scientific Reports designed and validated a positive-negative dual-polarity electrospinning device and directly compared single-polarity and dual-polarity operation. The study provides valuable experimental evidence for understanding the role of negative high voltage.

Paper: Development and validation of a dual-polarity electrospinning device for reproducible nanofiber fabrication

DOI: 10.1038/s41598-026-63448-5

What Is the Difference Between Single- and Dual-Polarity Electrospinning?

A conventional single-polarity electrospinning system typically uses the following connections:

·     The spinneret is connected to positive high voltage.

·     The collector is grounded.

·     The entire potential difference is supplied from the positive side.

For example, if the spinneret is set to +20 kV and the collector is at 0 V, the total potential difference between them is 20 kV.

A dual-polarity system uses a different arrangement:

·     The spinneret is connected to positive high voltage.

·     The collector is connected to negative high voltage.

·     The total potential difference is established jointly by the positive and negative electrodes.

For example, if the spinneret is at +10 kV and the collector is at -10 kV, the total potential difference is also 20 kV.

From this simple calculation, the total potential difference is exactly the same. Does that mean the electrospinning behavior must also be identical?

The paper's answer is: not entirely.

Both configurations still form a Taylor cone and exhibit jet whipping. Under the reported test conditions, the dual-polarity configuration produced a smaller, more confined whipping envelope rather than a perfectly straight jet.

Dual Polarity Does Not Simply Make the Electric Field “Stronger”

The researchers first used COMSOL Multiphysics to perform finite-element simulations of the two high-voltage configurations.

The following conditions were compared:

·     Single polarity at +10 kV versus dual polarity at +/-5 kV.

·     Single polarity at +15 kV versus dual polarity at +/-7.5 kV.

·     Single polarity at +20 kV versus dual polarity at +/-10 kV.

The total potential differences in these three comparisons were 10 kV, 15 kV, and 20 kV, respectively.

The simulations showed that, when the total potential difference was the same, the maximum electric-field strengths generated by the single- and dual-polarity configurations were virtually identical.

This result is important.

It shows that the purpose of adding a negative high-voltage supply is not simply to double the electric-field strength.

At the same total potential difference, the macroscopic maximum field strength can remain the same. What the dual-polarity configuration really changes is how positive and negative potentials are assigned between the spinneret and collector, together with the local electrostatic environment surrounding the jet.

Why Does Potential Distribution Affect the Jet?

Electrospinning is not governed by voltage magnitude alone.

From Taylor-cone formation to jet stretching, thinning, whipping, and final deposition, the process is controlled by several interacting forces, including:

·     Electrostatic force.

·     Surface tension.

·     Viscous resistance.

·     Viscoelasticity of the polymer solution.

·     Coulomb repulsion between charges on the jet surface.

·     Axial tensile force along the jet.

In a conventional single-polarity system, the spinneret is held at positive high voltage and the collector is grounded. The entire potential difference is established between one energized electrode and one zero-potential electrode.

In a dual-polarity system, positive and negative potentials are applied to the spinneret and collector, respectively. Although the total potential difference may remain unchanged, the potential is distributed between the two electrodes, and the local field components and electrostatic stresses acting on the jet may also change.

The paper proposes that dual-polarity operation can redistribute electrostatic stresses so that electrostatic force acts more effectively along the jet axis. This may influence:

1.   Taylor-cone formation and stability.

2.   Axial jet stretching and rapid thinning.

3.   The growth of lateral perturbations.

4.   The whipping envelope and deposition area.

5.   The transition from stable fibers to beads or electrospraying.

Negative high voltage should therefore be understood not simply as “more voltage,” but as an additional means of controlling electric-potential distribution and jet dynamics.

The Dual-Polarity Deposition Area Was Reduced by Approximately 70%

The researchers used a PCL solution to compare single- and dual-polarity electrospinning under otherwise identical experimental conditions.

The single-polarity system produced a larger fiber-deposition area and greater variation between repeated trials. The dual-polarity system produced a substantially smaller and more localized deposition area.

The reported results were:

·     Mean single-polarity deposition area: 8.002 +/- 1.548 cm^2.

·     Mean dual-polarity deposition area: 2.395 +/- 0.397 cm^2.

The dual-polarity configuration reduced the fiber-deposition area by approximately 70%.

A smaller, more localized deposition footprint indicates that the jet remained closer to the central axis during flight and that the lateral spread associated with whipping was partially suppressed. It does not mean that whipping disappeared.

For experiments that require greater control of deposition position, more uniform fiber coverage, or improved process repeatability, this change can have practical value.

Dual Polarity Does Not Mean “The Higher the Voltage, the Better”

The paper also reports an important limitation: although the dual-polarity configuration improved jet confinement, it made the process more sensitive to changes in voltage.

Under the reported experimental conditions, the optimum fiber-forming region shifted toward lower voltages in dual-polarity operation. As voltage increased further, beads, fused deposits, and eventually electrospraying appeared earlier.

Dual-polarity electrospinning should therefore not be interpreted as:

Turn on both positive and negative high voltage, keep increasing the voltage, and the fibers will automatically improve.

A more accurate interpretation is that dual-polarity operation changes the transmission and distribution of electrostatic stress, so the original process window also changes. When positive and negative high voltage are used together, the voltage combination, solution concentration, flow rate, working distance, and environmental conditions must be optimized again.

Dual polarity provides additional process-control freedom; it does not automatically guarantee better fibers under every set of parameters.

Why Does the TL-01 Use Single Polarity While Other Tongli Models Use Dual Polarity?

The Tongli TL-01 is an entry-level electrospinning system with a single-polarity high-voltage configuration.

A single-polarity architecture is simple, intuitive to operate, and easy to learn. It is fully capable of supporting routine electrospinning education, preliminary material screening, formulation validation, and experiments that do not require highly localized deposition.

Single polarity therefore does not mean that a system “cannot electrospin” or that it is technologically outdated. In fact, a large body of classic electrospinning research was completed using single-polarity systems.

As research requirements become more demanding, however, users may need to:

·     Adjust the potentials of the spinneret and collector more flexibly.

·     Improve spatial confinement of the jet.

·     Reduce the deposition area.

·     Improve process repeatability.

·     Investigate how positive and negative polarity influence fiber formation.

·     Conduct experiments with multiple spinnerets, conjugate spinnerets, coaxial spinnerets, or complex collectors.

·     Establish more suitable electric-field conditions for different materials.

To support these needs, other Tongli electrospinning models are equipped with positive and negative dual-polarity high-voltage power supplies.

A dual-high-voltage system can establish a positive-negative potential difference according to experimental requirements and provides the electrical foundation for more complex spinnerets, collectors, and process modules.

In other words:

The TL-01 single-polarity configuration emphasizes simplicity, practicality, and essential experimental capability. Tongli's other dual-polarity models emphasize greater process freedom and more advanced control of the electric field and jet behavior.

What Are the Core Benefits of Negative High Voltage?

Based on the simulations and experiments reported in this paper, the role of a negative high-voltage supply can be summarized in five points.

1. More Flexible Potential Distribution

The total potential difference no longer has to be supplied entirely from the spinneret side; it can be distributed between the spinneret and collector.

2. A Modified Electrostatic Environment Around the Jet

Even when the total potential difference and maximum field strength are the same, the positive-negative potential assignment may still alter local field components and electrostatic stresses.

3. Improved Spatial Confinement of the Jet

In the reported experiments, the dual-polarity configuration reduced the mean deposition area by approximately 70%, producing a more localized fiber deposit.

4. An Additional Process-Control Dimension

Researchers can adjust the positive and negative voltages independently and observe how different potential combinations affect the Taylor cone, jet, and fiber morphology.

5. A Foundation for More Complex Processes

A dual-polarity high-voltage system is better suited to further expansion into multi-spinneret, conjugate-spinning, oriented-collection, and complex electric-field-control studies.

Conclusion

Whether an electrospinning system needs negative high voltage cannot be judged only by the maximum kilovoltage printed in its specifications.

The more important question is whether the research requires more flexible control over potential distribution, jet trajectory, and fiber-deposition behavior.

The Scientific Reports study shows that the advantages of dual-polarity electrospinning do not arise from a simple increase in maximum electric-field strength. Instead, they are primarily associated with redistribution of electric potential and electrostatic stress.

At the same total potential difference, a positive-negative dual-polarity configuration can produce different jet dynamics and, in the reported experiments, a more localized deposition area. At the same time, its optimum process window may shift toward lower voltage, making renewed parameter optimization necessary.

Negative high voltage is therefore not merely a specification added to increase an equipment rating. It is a technical tool that expands electrospinning process-control capability.

For basic education and routine electrospinning, a single-polarity system remains simple, reliable, and practical. For experiments requiring deeper investigation of jet stability, electric-field distribution, and complex fiber structures, a positive-negative dual-polarity system provides a broader process space.

Reference

Kevin Stalin Catzim Ríos, Amin Orash Mahmoudsalehi, and Wendy de Lourdes Ortega-Lara. “Development and validation of a dual-polarity electrospinning device for reproducible nanofiber fabrication.” Scientific Reports (2026).

DOI: 10.1038/s41598-026-63448-5