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

Abstract

Abstract-This work is aimed toward the goal of investigating the influence of different materials on the signal-to-noise ratio (SNR) of passive neural microelectrode arrays (MEAs). Noise reduction is one factor that can substantially improve neural interface performance. The MEAs are fabricated using gold, indium tin oxide (ITO), and chemical vapor deposited (CVD) graphene. 3D-printed Nylon reservoirs are then adhered to the glass substrates with identical MEA patterns. Reservoirs are filled equally with a fluid that is commonly used for neuronal cell culture. Signal is applied to glass micropipettes immersed in the solution, and response is measured on an oscilloscope from a microprobe placed on the contact pad external to the reservoir. The time domain response signal is transformed into a frequency spectrum, and SNR is calculated from the ratio of power spectral density of the signal to the power spectral density of baseline noise at the frequency of the applied signal. We observed as the magnitude or the frequency of the input voltage signal gets larger, graphene-based MEAs increase the signal-to-noise ratio significantly compared to MEAs made of ITO and gold. This result indicates that graphene provides a better interface with the electrolyte solution and could lead to better performance in neural hybrid systems for in vitro investigations of neural processes.

Peripheral Neuron Survival and Outgrowth on Graphene

“…Neural conductive interfaces for neural regeneration application usually exploit conductive polymers, such as polyethylenedioxythiophene (PEDOT) and polypyrrole (PPy), or composite materials whose conductivity depends on the inclusion of graphene or carbon nanotubes (CNTs) (Schmidt et al, 1997 ; Deng et al, 2011 ; Pinho et al, 2016 ). Recently, graphene and carbon nanotubes (CNTs) have been successfully used to improve recording and electrical stimulation of neurons (Keefer et al, 2008 ; Kuzum et al, 2014 ) and surprisingly neural microelectrode arrays (MEAs) fabricated using graphene performed better than gold and indium tin oxide (ITO), in terms of signal-to-noise ratio (SNR) (Rastegar et al, 2017 ).…”

Graphene-based nanomaterials for peripheral nerve regeneration

“…The use of CVD graphene, with or without a polymeric coating is actually preferred to realize 2D devices as planar transparent electrodes to stimulate and record neural activity. Indeed, recently graphene and CNTs have been successfully used to improve recording and ES of neurons ( Keefer et al, 2008 ; Kuzum et al, 2014 ) and, surprisingly, neural microelectrode arrays (MEAs) fabricated using graphene obtained via CVD performed better than gold and indium tin oxide (ITO), in terms of signal-to-noise ratio ( Rastegar et al, 2017 ). Park et al developed a CVD graphene-based, carbon-layered electrode array device that was implanted in rodent brain for high-resolution neurophysiological recording.…”

Graphene-based cardiac sensors and actuators

“…Incorporation of graphene into recording electrodes leads to a significant reduction in their impedance and an increase in their charge injection capacity ( Kireev et al, 2017b ) . The SNR for graphene electrodes is approximately six times lower than for gold electrodes, ensuring the significantly improved sensitivity of graphene-based recording systems ( Kuzum et al, 2014 ; Rastegar et al, 2017 ).…”