Ultra high-aspect-ratio neuroprobe: 5-μm-diameter and 400-μm-length needle detects action potentials in VIVO

摘要

This paper reports 5-μm-diameter and 400-μm-length ultra high-aspect-ratio needle electrodes for neuronal action potential recordings in vivo. The needle-electrode was vertically assembled on a 1 × 1 mm2 block module of silicon by vapor-liquid-solid (VLS) silicon growth technology for ~ 7 hours. After metallization and encapsulation of the needle, the module device was packaged for in vivo animal experiments. The fabricated needle-electrode, which has an electrical impedance of 328 kΩ at 1 kHz, shows the smooth tissue penetration and neural recording capabilities, as demonstrated by the needle penetration and recording action potentials of a mouse's cortex in vivo. To the author's knowledge, this is world's smallest extracellular recording needle, which will offer numerous electrophysiological recording applications while the brain tissue damage can be reduced. As a future work, the fabricated needle module device will further be minimized and arranged in an array of high dense needles with 100% device yield, while other functionalities (drug delivery and optogenetic applications) will be integrated with the same needle array.