What is a bipolar setup?

• A. Two different sizes
• B. Two of equal size
• C. One large and one small
• D. Three electrodes total

Answer: (B)

In a bipolar setup, two electrodes are used to create the current pathway, and they act as the active pair with current flowing directly between them. Using two equal-size electrodes is important because it makes the impedance at each site similar. When impedance and contact area are balanced, the current density—how much current per unit area—is evenly distributed under both pads. This keeps the stimulation localized between the two electrodes and makes the path of the current predictable and safe.

If the electrodes are different sizes, the smaller one will have higher current density, and the larger one will carry less, causing the current to favor one side. This can lead to uneven stimulation, discomfort, and less precise targeting. Also, having three electrodes would not be a bipolar setup; that would be a different configuration requiring more pads.

So, using two equal-size electrodes best achieves balanced, controlled stimulation between the two pads.