Graphene microelectrode arrays for neural activity detection

Abstract

We demonstrate a method to fabricate graphene microelectrode arrays (MEAs) using a simple and inexpensive method to solve the problem of opaque electrode positions in traditional MEAs, while keeping good biocompatibility. To study the interface differences between graphene-electrolyte and gold-electrolyte, graphene and gold electrodes with a large area were fabricated. According to the simulation results of electrochemical impedances, the gold-electrolyte interface can be described as a classical double-layer structure, while the graphene-electrolyte interface can be explained by a modified double-layer theory. Furthermore, using graphene MEAs, we detected the neural activities of neurons dissociated from Wistar rats (embryonic day 18). The signal-to-noise ratio of the detected signal was 10.31±1.2, which is comparable to those of MEAs made with other materials. The long-term stability of the MEAs is demonstrated by comparing differences in Bode diagrams taken before and after cell culturing.

Electrochemical Characterization of Graphene Microelectrodes for Biological Applications

“…All studies report low noise and high signal‐to‐noise ratio (SNR) for cultures or tissues of various cell types in vitro as well as for in vivo applications. Some studies report favorable properties of graphene electrodes regarding long‐term stability and corrosion resistance . In one study, several layers of graphene are transferred step‐by‐step, forming a 4‐layer system on the electrode site .…”

“…The so far investigated graphene electrodes are usually large and show correspondingly low impedance values. Only three studies present graphene microelectrodes, but they show contradictory impedance results ,,. This, together with a lack of comparability due to different electrode sizes and substrates, leads to few reliable and conclusive results regarding graphene electrodes.…”

Versatile Flexible Graphene Multielectrode Arrays

“…Impedance of the GMEAs, of 20 µm in diameter, measured at 1 kHz is around 1 ± 0.5 × 10 5 Ω, which is in the range of previously reported values [24,25,31,32]. In order to fit the GMEA’s behavior, one has to consider another constant phase element (compared to metal electrodes), representing quantum capacitance [33,34,35].…”

“…The two constant phase elements represent the electrical double-layer and quantum capacitance. In previous works [24,31], a Warburg element was used to model linear diffusion. However, in our case, the electrode diameter is too small to be described by linear diffusion; therefore, the Warburg element was not used in our calculations.…”

Signal-to-noise ratio enhancement using graphene-based passive microelectrode arrays

“…Microelectrode arrays (MEAs) have been rapidly gaining interest because they are able to electrically stimulate neuronal cells in vitro and in vivo. Additionally, they can be used to easily record the activity of cells at multiple points without rupturing them, in contrast to patch clamp techniques which cannot be used for long duration and are limited to a single cell measurements [2][3][4][5].…”