Nanoneedle-Electrode Devices for In Vivo Recording of Extracellular Action Potentials

Microscale needle-like electrode technologies offer extracellular recording with a high spatiotemporal resolution. Further miniaturization of needles to nanoscale minimizes tissue injuries; however, a reduced electrode area increases electrical impedance that degrades the quality of neuronal signal recording. We overcome this limitation by fabricating a 300 nm tip diameter and 200 μm long needle electrode where the amplitude gain with a high-impedance electrode (>15 MΩ, 1 kHz) was improved from 0.54 (-5.4 dB) to 0.89 (-1.0 dB) by stacking it on an amplifier module of source follower. The nanoelectrode provided the recording of both local field potential (<300 Hz) and action potential (>500 Hz) in the mouse cortex, in contrast to the electrode without the amplifier. These results suggest that microelectrodes can be further minimized by the proposed amplifier configuration for low-invasive recording and electrophysiological studies in submicron areas in tissues, such as dendrites and axons.