jULIEs: nanostructured polytrodes for low traumatic extracellular recordings and stimulation in the mammalian brain

Abstract

Objective Extracellular microelectrode techniques are the most widely used approach to interrogate neuronal populations. Regardless of the manufacturing method, damage to the vasculature and circuit function during probe insertion remains a concern. Reducing the footprint of the penetrating probes is a potential solution to this issue. However, coupling to the extracellular signals requires careful surface engineering. Approach Here, we show that continuously drawn SiO2-insulated ultra-microelectrode fibres offer an attractive substrate to address these challenges. Individual fibres can be fabricated to >10m continuous stretches and a selection of diameters below 30 µm with a low resistance (<100 Ω/m), continuous metal core of <10 µm and atomically flat smooth shank surfaces. To optimize the properties of the miniaturised electrode-tissue interface, we electrodeposit rough Au structures followed by ~20nm IrOx film by electrodeposition resulting in reduction of the interfacial impedance to <500kΩ at 1 kHz. Main results We demonstrate that these ultra-low impedance electrodes (jULIEs) can record and stimulate single and multi-unit activity with minimal tissue disturbance and exceptional signal-to-noise ratio in both superficial (~40µm) and deep (~6mm) structures of the mouse brain. We further show that sensor modifications are stable and probe manufacturing is reproducible. Significance Minimally perturbing bidirectional neural interfacing can reveal circuit function in the mammalian brain in vivo.

Advanced Biomimetic Nanostructured Microelectrode Arrays for Enhanced Extracellular Recordings of Enteric Neurons

“…[12] This led to the emergence of synthetic durable nanostructures on microelectrode surfaces with conductive materials, which not just enhanced the cell-electrode interface, but also improved its signal transduction properties. [13][14][15] Another important aspect of developing nanostructured MEAs is the mismatch of physical properties between the biosensor and the neural tissue. MEAs developed for in vitro application are generally fabricated with metallic electrode surfaces deposited on brittle substrates such as glass or silicon.…”