On neural recording using nanoprotrusion electrodes

Abstract

Objective. Nano neuroelectrodes, often adopting a nanoprotrusion structure, are promising for improved chronic reliability and capability of both extracellular and intracellular recordings. However, a complete theoretical foundation has yet to be established, significantly impeding further developments and applications. This paper derives analytical solutions to this extracellular and intracellular recording problem of nanoprotrusion electrodes, unraveling the underlying recording mechanisms and elucidating the natures of different recordings. Approach. Advanced circuit modeling and analysis techniques from the electrical engineering discipline are introduced to this cutting-edge, interdisciplinary problem, and an analytical framework is developed to produce closed-form solutions that offer clear images on the recording mechanisms, nature of signals, and interplays between key interface parameters. Main results. The results show that the ‘intracellular-like’ recording after membrane poration contains fractions of both intracellular action potential (iAP) and extracellular field potential (eFP). When recording using multiple nanoprotrusion electrodes on the same conductive substrate, while the signal itself is only slightly enhanced, the recording is substantially enhanced, comparing to using a single electrode. Having the substrate unpassivated can distort the iAP component more with the eFP component, and the portion uncovered by cell can further severely compromise the recording quality. Significance. Through key conceptual breakthroughs, this present work advanced our prior knowledge on this topic to a critical level capable of deriving closed-form analytical solutions. These findings are significant to advance the theory and practice of nano neuroelectrode technologies.