nanoelectrodes

Nanoelectrodes are electrical probes with tip dimensions on the nanometer scale designed to interface with biological systems at the cellular or subcellular level. They are used to record electrical activity or sense chemical species with high spatial resolution, complementing conventional microelectrodes in neuroscience, electrophysiology, and biosensing.

Common designs include nanopipettes with sharpened glass or quartz tips, carbon-fiber or carbon-nanotube tips, and nanoscale metal tips fabricated by sharpening and plating. Nanoelectrode arrays integrate many nanoscale electrodes on a single substrate for parallel measurements. Fabrication methods range from chemical etching and laser pulling to obtain sharp tips, to focused ion beam milling, electrochemical deposition to tailor surface properties, and lithographic processes for arrays. Materials frequently used are carbon-based electrodes (carbon fibers, nanotubes, graphene), noble metals (gold, platinum), and conducting polymers. Impedance and signal characteristics depend on tip area and surface treatment, with smaller tips generally presenting higher impedance and higher thermal noise.

Applications span intracellular recording from neurons using penetrating nanoelectrodes, extracellular mapping with subcellular resolution, and neurochemical sensing through voltammetry or amperometry. Nanoelectrode arrays enable high-throughput measurements in brain tissue or cultured cells, and are used in scanning probe techniques for nanoscale imaging and analysis of biological processes.

Advantages include high spatial resolution, potential for reduced tissue damage, and access to subcellular compartments. Limitations involve higher impedance, increased noise, mechanical fragility, and greater fabrication and handling complexity. Biocompatibility, stability, and long-term recording performance remain active areas of development.