Shape the contact. Explore the field.

Four geometries. Three sizes. The same injected current.

Explore how a disk, square, long rectangle and ring distribute electrical potential and electric-field magnitude through tissue. Every map uses the same physical axes and one shared color scale.

Preparing field maps…

Linear color scale, shared across all visible maps. It updates when the comparison changes. Dashed white outlines are contact footprints projected onto the top slice. Gray cells are outside the sampling guard.

Move over a map, or focus it and use arrow keys, to inspect a location.

What you are looking at

Potential is the extracellular voltage relative to a distant return. Electric field is how quickly that voltage changes with position: E = −∇V. The magnitude shows strength, not direction. Reversing current reverses potential and field direction; it leaves field magnitude unchanged.

At equal area, all contacts inject the same total current. Their shapes redistribute current near the contact, while their distant fields approach the same half-space point-source limit. In the size comparison, increasing contact area spreads the same current over more surface. Compare both near and far from the contacts.

Model and limits

Independent field comparison and retained failures → A separate finite-volume solver now checks selected locations; this evidence does not validate every displayed pixel or neuronal activation.

This is a new exploratory boundary-element model: one equipotential planar conductor, homogeneous isotropic tissue (0.3 S/m), an insulating plane outside the contact, and a return at infinity. Panel currents are solved, not assumed uniform. All shapes have exactly the selected exposed area in the panel model; curved boundaries are approximated with small rectangles.

Samples are restricted to heights at least 0.2 times the equivalent disk radius. This avoids displaying the unresolved sharp-edge surface singularity; it is a numerical sampling guard, not a biological safety boundary. The ring’s center is insulating tissue boundary, not a second electrode. No shank, interface impedance, layered tissue, finite return contact or multi-contact interaction is included.

Disk potential and field are checked against an analytical reference; every shape has mesh-refinement and integration checks. These are sampled numerical checks, not a proof of accuracy everywhere. This gallery is separate from the finite-disk neuron replay and does not establish activation thresholds or selective stimulation.

Method and reproducibility · Numerical results · Download solved panel currents