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

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 mu m base diameter, 400 mu m height). The process has additionally been extended to realize smaller electrodes (30 mu m x 30 mu m) at a height of 400 mu m 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 k Omega to 670 Omega for the microtower electrodes and 55 to 39 k Omega for the 30 mu m x 30 mu m 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 (similar to 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.

Automated summary

A nontraditional fabrication technique for 3D microelectrode arrays capable of interfacing with 3D cellular networks in vitro has been presented. The technology uses cost-effective makerspace microfabrication techniques and has been characterized for electrical, chemical, electrochemical, biological, and chip hydration stability performance metrics. The fabricated 3D MEAs are rapidly produced with minimal cleanroom usage and are fully functional for electrical interrogation of organ-on-a-chip models for pharmaceutical screening and toxicity testing in vitro.