RESUMO
Investigations into mechanisms in various cortical areas can be greatly improved and supported by stable recording of single neuronal activity. In this study, fine silicon wire electrodes (diameter 3 µm, length 160 µm) are fabricated by vapor-liquid-solid (VLS) growth with the aim of stabilizing recording and reducing the invasiveness on the measurement procedure. The electrode is fabricated on a modular 1 × 1 mm2 conductive silicon block that can be assembled into a number of different device packages, for example on rigid or flexible printed circuit boards (PCB). After plating with a 5 µm diameter platinum black, the needle exhibits an electrical impedance of ~100 kΩ at 1 kHz in saline. The in vivo recording capability of the device is demonstrated using mice, and spike signals with peak-to-peak amplitudes of 200-300 µV in the range 0.5-3 kHz are stably detected, including single-unit activities in cortical layer 2/3. In addition, the device packaged with a flexible PCB shows stable unit recordings for 98.5 min (n = 4). Consequently, our modular, low-invasive needle electrode block devices present an effective route for single-unit recordings in vivo, as well as demonstrating adaptability in device design for a diverse range of experiments.
