Interface design guide

Getting started

1. Generate a grid, line, staggered array, circle, arc, concentric pattern, perimeter or spiral. Counts are capped at 4,096 for browser performance. A single contact is allowed.
2. Set contact size and center-to-center pitch. Add more patterns or place single contacts. Box-select a subset and change its shape, size, position, exit side or metal layer in the Selection tab.
3. Pick a connector-bank arrangement, trace width, clearance and number of metal planes. Compare completed routes, total length and assumed trace resistance.
4. Look at unresolved airwires and rule findings. Try more exit sides, a different pad order, narrower traces within your process rules, or a smaller array.
5. Save the JSON to keep an editable design. Export single metal planes, contact openings and substrate footprints for review.

Shift-click adds or removes contacts from the selection. Arrow keys nudge, shift-arrow moves ten grid steps, Ctrl/Cmd-Z undoes, scroll zooms at the pointer and space-drag pans. The ID list and numeric fields in the Selection tab work without a pointer. Designs are saved in the browser.

Contact geometry

Circles, squares, rectangles, ellipses and rings trade off area, perimeter and packing. Area is computed exactly: a circle is πd²/4 and a ring is π(D² − d²)/4. A ring lead lands on the conductive annulus, not the hole.

Rings and other high-perimeter shapes show up in studies of platinum contacts and deep brain stimulation, but the results depend on material, surface structure, electrolyte and stimulation conditions. The designer reports geometry and does not pick a best shape or an impedance. [4] [5] Impedance also scales differently by material. [7]

Grids are easy to index, staggered layouts change neighbor distances, lines sample along one axis and circles sample around a center. Choosing pitch for a real target also depends on anatomy, signal bandwidth, recording depth and a field model, none of which this tool has.

Geometric area is not electrochemically active area. A porous coating or rough surface does not show up in a 2D outline. Contact rotation is separate from array rotation. Overlap checks are exact for circles and rings and use axis-aligned envelopes for other shapes, so some rotated shapes get conservative warnings.

Lead exits, pad order and channels

Each electrode is its own net with a unique channel and pad. "Interleaved" describes where leads exit. It never joins electrodes together. These arrangements are heuristics built into the editor. The source papers do not show any of them to be better.

Position order places pads along the bank by contact position. Creation order keeps the channel sequence. Reverse, column and row-serpentine orders give other pin mappings. Pad order changes congestion even when the contacts do not move. A row-serpentine pin order is not a serpentine trace.

The router is a clearance-aware orthogonal search with conservative contact and pad envelopes. It routes outer contacts first, tries each plane for automatic assignments, and smooths corners only where the sampled route stays clear. Direct straight leads are checked, not assumed connected. Red dashed airwires have no completed path.

It is a bounded heuristic, not an optimal autorouter, and routing order can miss valid paths. Large layouts use a coarser grid and a fixed search budget. Unresolved contacts stay in the netlist with their status. Add planes, move banks or adjust spacing before treating a layout as connected.

Straight, rounded and serpentine leads

Straight leads have the shortest centerline for fixed endpoints but can cross other contacts or traces. Orthogonal leads give predictable corridors. Rounded leads replace corners with sampled quadratic curves. Corner setback sets where the curve starts, not a guaranteed bend radius.

Serpentine cables can lower stiffness and take up displacement. Sankar et al. measured higher compliance in a complete serpentine polyimide interconnect than in the straight design they compared. The result depends on the cable geometry, thickness and loading, and the paper does not show that rounding a trace improves chronic tissue response. [2]

More recent work compares linear, serpentine and open-lattice thin-film ribbon cables with a-SiC / polyimide structure and Ti / Au traces. Bending tolerance and tensile extensibility are separate properties, and the architecture around the traces matters. [3]

Here, the serpentine option adds a smooth wave to the longest eligible segment, and the conformal-ribbon substrate adds margin around the resulting paths. Both are geometry only. There is no finite-element strain, fatigue, adhesion, encapsulation, tissue response or biocompatibility model. A metal wave on a wide continuous substrate is not automatically a compliant cable.

Photolithography and the multilayer stack

A thin-film interface needs patterned conductor and insulator layers, openings for the recording or stimulation sites, and a substrate outline. Photosensitive-polyimide processing shows how those layers support different electrode architectures. [1] The editor keeps metal, openings and substrate as separate exports for that reason.

A 2026 high-channel-count μECoG platform reports four metal routing layers, 1,344 channels per layer, 2 µm minimum linewidth and 2.5 µm minimum spacing in its own process. [6] Those two numbers are the only thing borrowed from it. The device, metal thicknesses, via technology, alignment and yield are not reproduced. The default 3 / 3 µm rules are placeholders you can edit.

More metal planes open more routing corridors. A contact, its trace and its pad stay on one plane. Shapes on different planes are treated as electrically isolated, but the tool generates no vias, interlayer dielectric or process-specific openings. The openings export is a nominal plan-view template, not a qualified multilayer opening sequence.

The gold / platinum conductor and polyimide / Parylene-C / SU-8 options are labels for your assumptions and do not change the geometry. A real mask set needs the foundry's minimum widths and gaps, overlay allowances, alignment marks, etch or lift-off bias, pad finishes, passivation overlaps, minimum radii and release and packaging constraints. The built-in checks cover only some of these.

Exports

Coordinates are in micrometers. SVG viewBox units match, and the outer width and height are in millimeters so the file keeps its physical size. Rounded and serpentine centerlines export as sampled polylines. Trace thickness is not modeled and substrate thickness is metadata. The screen enforces a minimum visible line width for inspection at low zoom, while the SVG keeps the requested trace width.

Estimated trace resistance is R = (length / width) × R_sheet. The 0.2 Ω/□ default is an assumed value and does not change with the material label. It leaves out electrode / electrolyte impedance, connector resistance, parasitic capacitance, leakage and frequency effects.

This version outputs editable geometry and a netlist for downstream simulation. It cannot yet load a custom design into the cortical recording lab or the peripheral-nerve sandbox. Keep the JSON to retain every layout and routing assumption.

Sources

Reviewed 5 October 2026. Measured results from the papers are kept separate from the editor's own routing choices.