Three-micrometer-diameter needle electrode with an amplifier for extracellular in vivo recordings

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 118; no. 16; pp. 1 - 11
• Main Authors: Kita, Yuto, Tsuruhara, Shuhei, Kubo, Hiroshi, Yamashita, Koji, Seikoba, Yu, Idogawa, Shinnosuke, Sawahata, Hirohito, Yamagiwa, Shota, Leong, Xian Long Angela, Numano, Rika, Koida, Kowa, Kawano, Takeshi
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 20.04.2021
• Subjects: Amplification; Amplifiers; Bluetooth; Brain damage; Electrical impedance; Electrical properties; Electrodes; Electrophysiological recording; Impedance; Modules; Physical Sciences; Recording; Signal to noise ratio; Silicon; Surgical implants; Voltage gain; MOSFET; microelectrode; neural recording
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2008233118

Microscale needle-electrode devices offer neuronal signal recording capability in brain tissue; however, using needles of smaller geometry to minimize tissue damage causes degradation of electrical properties, including high electrical impedance and low signal-to-noise ratio (SNR) recording. We overcome these limitations using a device assembly technique that uses a single needle-topped amplifier package, called STACK, within a device of ∼1 × 1 mm². Based on silicon (Si) growth technology, a <3-μm-tip-diameter, 400-μm-length needle electrode was fabricated on a Si block as the module. The high electrical impedance characteristics of the needle electrode were improved by stacking it on the other module of the amplifier. The STACK device exhibited a voltage gain of >0.98 (−0.175 dB), enabling recording of the local field potential and action potentials from the mouse brain in vivo with an improved SNR of 6.2. Additionally, the device allowed us to use a Bluetooth module to demonstrate wireless recording of these neuronal signals; the chronic experimentwas also conducted using STACK-implanted mice.