Development of multi-depth probing 3D microelectrode array to record electrophysiological activity within neural cultures

Abstract

Microelectrode arrays (MEAs) play a crucial role in investigating the electrophysiological activities of neuronal populations. Although two-dimensional neuronal cell cultures have predominated in neurophysiology in monitoring in-vitro the electrophysiological activity, recent research shifted toward culture using three-dimensional (3D) neuronal network structures for developing more sophisticated and realistic neuronal models. Nevertheless, many challenges remain in the electrophysiological analysis of 3D neuron cultures, among them the development of robust platforms for investigating the electrophysiological signal at multiple depths of the 3D neurons’ networks. While various 3D MEAs have been developed to probe specific depths within the layered nervous system, the fabrication of microelectrodes with different heights, capable of probing neural activity from the surface as well as from the different layers within the neural construct, remains challenging. This study presents a novel 3D MEA with microelectrodes of different heights, realized through a multi-stage mold-assisted electrodeposition process. Our pioneering platform allows meticulous control over the height of individual microelectrodes as well as the array topology, paving the way for the fabrication of 3D MEAs consisting of electrodes with multiple heights that could be tailored for specific applications and experiments. The device performance was characterized by measuring electrochemical impedance, and noise, and capturing spontaneous electrophysiological activity from neurospheroids derived from human induced pluripotent stem cells. These evaluations unequivocally validated the significant potential of our innovative multi-height 3D MEA as an avant-garde platform for in vitro 3D neuronal studies.

Influence of Ultrasonic Bath on Mold-Assisted Electrodeposition of Gold Microelectrode Arrays

“…We focus specifically on the deposition of gold microstructures commonly used in 3D MEAs due to their biocompatibility and electrical conductivity. Our study builds on previous research on mold-assisted electrodeposition and ultrasonic vibrations' influence on various manufacturing processes [4,5]. In ultrasonic bath-assisted electrodeposition, the sound waves create microscopic bubbles in the liquid medium.…”

Enhancing the Deposition Rate and Uniformity in 3D Gold Microelectrode Arrays via Ultrasonic-Enhanced Template-Assisted Electrodeposition

“…An additive-free electroplating solution (AUROLYTE CN200, Atotech Deutschland GmbH & Co. KG, Berlin, Germany) was chosen for the electrodeposition experiments. Three types of planar MEAs arranged in a hexagonal pattern (as described in [ 22 ]) were used for the experiments: (S1) consisting of 60 electrodes with a diameter of 65 µm and a pitch of 265 µm, of which 21 were connected to a custom routing for electrodeposition; (S2) consisting of 60 electrodes with a diameter of 65 µm and a pitch of 265 µm, of which 41 were connected to a custom routing for electrodeposition; and (S3) consisting of 60 electrodes with a diameter of 35 µm and a pitch of 195 µm, of which 44 were connected to a custom routing for electrodeposition. A thick negative-type photoresist (KMPR-1035, Kayaku Advanced Materials, Inc., Westborough, MA, USA) was utilized for template fabrication.…”

“…Template-assisted electrodeposition utilizes a polymeric hard mask as a template to define the shape of the electrodeposited microstructures [ 18 , 19 , 20 , 21 ]. More recently, the development of multi-depth probing 3D MEAs with customizable microelectrode heights has been reported using the template-assisted electrodeposition technique [ 22 ]. Electrodeposited gold electrodes have a higher surface roughness compared to the electrodes developed using physical vapor deposition methods; this surface roughness translates to a larger electrochemically active area at the cell–electrode interface, promoting interactions between the cell and the electrode [ 4 ].…”

XMEA: A New Hybrid Diamond Multielectrode Array for the In Situ Assessment of the Radiation Dose Enhancement by Nanoparticles

“…Electrochemical biosensor arrays employing different materials and configurations and allowing chemical functionalization for different applications have been studied [ 22 , 23 , 24 , 25 , 26 ]. Also, diamond-doped electrodes as electrochemical sensors have been used for applications such as water treatment and the development of biosensors [ 27 , 28 ].…”