Electrode-neuron sealing resistance

The seal (or sealing) resistance is the electrical resistance of the thin cleft between the electrode surface and the neuronal membrane it records from, the tissue analogue of the gigaseal in patch clamp. A larger seal resistance forces more of the neuron's transmembrane current to flow across the electrode rather than leaking away through the cleft, so the recorded extracellular signal amplitude scales directly with it.

For a passive extracellular contact the seal is loose (of order megaohms or less) and signals are small; the whole point of tight-coupling strategies, such as engulfment by mushroom-shaped or nanopillar electrodes, cell-penetrating nanowires, and adhesion-promoting coatings, is to raise the seal resistance toward the near-intracellular regime. Seal resistance thus links the materials and geometry of the interface directly to signal quality, and is the quantitative target of nanoscale coupling.