Maskless production of neural-recording graphene microelectrode arrays

Abstract

This paper describes the production of a new version of high-performance microelectrode arrays (MEAs) that can be custom produced and used to explore in vitro neural networks. The MEAs were manufactured using direct write technology and comprised graphene microelectrodes and SU-8 insulation on a glass substrate, where graphene was grown by chemical vapor deposition on copper foil and then transferred to the substrate. The graphene MEAs experimentally exhibited adequate electrical specifications, with the electrode characterized using noise testing, cyclic voltammetry, and impedance spectroscopy. The MEAs herein exhibited improved properties over those previously reported in the literature. The average impedance at 1 kHz for the electrodes herein was 5.2 kΩ, which is compatible with commercial MEAs which present values between 30 and 400 kΩ. Further, the MEA device herein did not show biotoxicity and is thus adequate for cellular potential measurements.

Graphene microelectrode arrays, 4D structured illumination microscopy, and a machine learning-based spike sorting algorithm permit the analysis of ultrastructural neuronal changes during neuronal signalling in a model of Niemann-Pick disease type C

“…Graphene, i.e., a monolayer of carbon atoms tightly arranged in a honeycomb structure 12 , exhibits good electrical conductivity 13 , which is also frequency-independent up to microwave frequencies 14 , making it suitable for the detection of spontaneous neuronal activity 15,16 . Furthermore, its biocompatibility permits long-term cultivation of cells 15,[17][18][19][20][21] , which is another requisite for long-term recordings of neuronal signals. However, most importantly, a single layer of graphene has a transparency of 97.7 % in the visible light spectrum, with a negligible reflectance of less than 0.1 % 22 , which is, thus far, the highest transparency measured amongst all electrode materials used for transparent MEAs.…”