Fabrication and Characterization of 3D Printed, 3D Microelectrode Arrays for Interfacing with a Peripheral Nerve-on-a-Chip

Abstract

We present a nontraditional fabrication technique for the realization of three-dimensional (3D) microelectrode arrays (MEAs) capable of interfacing with 3D cellular networks in vitro. The technology uses cost-effective makerspace microfabrication techniques to fabricate the 3D MEAs with 3D printed base structures with the metallization of the microtowers and conductive traces being performed by stencil mask evaporation techniques. A biocompatible lamination layer insulates the traces for realization of 3D microtower MEAs (250 μm base diameter, 400 μm height). The process has additionally been extended to realize smaller electrodes (30 μm × 30 μm) at a height of 400 μm atop the 3D microtower using laser micromachining of an additional silicon dioxide (SiO2) insulation layer. A 3D microengineered, nerve-on-a-chip in vitro model for recording and stimulating electrical activity of dorsal root ganglion (DRG) cells has further been integrated with the 3D MEA. We have characterized the 3D electrodes for electrical, chemical, electrochemical, biological, and chip hydration stability performance metrics. A decrease in impedance from 1.8 kΩ to 670 Ω for the microtower electrodes and 55 to 39 kΩ for the 30 μm × 30 μm microelectrodes can be observed for an electrophysiologically relevant frequency of 1 kHz upon platinum electroless plating. Biocompatibility assays on the components of the system resulted in a large range (∼3%–70% live cells), depending on the components. Fourier-transform infrared (FTIR) spectra of the resin material start to reveal possible compositional clues for the resin, and the hydration stability is demonstrated in in-vitro-like conditions for 30 days. The fabricated 3D MEAs are rapidly produced with minimal usage of a cleanroom and are fully functional for electrical interrogation of the 3D organ-on-a-chip models for high-throughput of pharmaceutical screening and toxicity testing of compounds in vitro.

Design and engineering of organ-on-a-chip

“…To minimize the mechanical mismatch at the interface between the cells and the electrodes, MEAs have been coated with bioactive hydrogels or fabricated with soft electrode materials [ 88 ]. Further, 3D printing technology has enabled the fabrication of high-resolution MEAs on soft substrate [ 88 ] and 3D microtower MEAs [ 85 ] in a time- and cost-efficient manner.…”

Modeling Neurodegenerative Diseases Using In Vitro Compartmentalized Microfluidic Devices

“…Microfluidic devices used for neuroscience research are usually fabricated using a combination of SU-8 photolithography and soft lithography techniques (Campenot, 1977;Park et al, 2006). Recently, 3D printing techniques to produce microfluidic devices have gained importance, since their ability for a faster and lower-cost fabrication makes them an attractive alternative to conventional microfabrication protocols (Kundu et al, 2020). These techniques allowed the fabrication of microfluidic device's chambers and microchannels (Ren et al, 2013).…”

Copper–Ruthenium Composite as Perspective Material for Bioelectrodes: Laser-Assisted Synthesis, Biocompatibility Study, and an Impedance-Based Cellular Biosensor as Proof of Concept

“…[ 2 ] p. 70 and refs. [ 45 , 46 , 47 ]). Despite the remarkable electrochemical properties and biocompatibility of the noble metals, there are also disadvantages such as their expensiveness and difficulties in processing [ 40 ].…”