Abstract:
Microelectrode arrays (MEAs) are essential tools for recording and stimulating electrogenic tissues, but their fabrication typically depends on complex, costly, and mask-based cleanroom processes.
While inkjet-printed MEAs have increasingly been explored as low-cost alternatives, most demonstrations have focused on cardiac cell recordings, with only a limited number of studies showing neuronal recordings. Furthermore, no work to date has demonstrated neuronal interfacing, combining single-unit recording with electrical stimulation, using inkjet-printed MEAs.
Here, we investigate whether inkjet-printed MEAs enable both extracellular single-unit neuronal recording and reliable electrical stimulation. We fabricated gold microelectrodes on flexible foils via maskless inkjet-printing, insulated them with printed SU-8 (an epoxy-based dielectric), and characterized their morphology using scanning electron microscopy, atomic force microscopy, and profilometry, and their electrochemical behavior using impedance spectroscopy and cyclic voltammetry. The printed gold formed a rough nanoparticle-based morphology, resulting in an increased effective electrochemical surface area. This morphology enabled low electrode impedances and high charge injection during voltage-controlled stimulation.
We assessed functional performance in ex vivo retinal tissue. The inkjet-printed MEAs enabled reliable single-unit recordings with signal-to-noise ratios comparable to cleanroom-fabricated commercial devices and cell activation upon electrical stimulation with biphasic pulses. The electrodes were reusable and noncytotoxic, verified via a standard cell viability assay. These results establish the first inkjet-printed microelectrodes capable of neuronal interfacing, demonstrating that printed MEAs can match the functional performance of conventional microfabricated devices.
This work positions inkjet-printing as a scalable, easily adaptable, low-cost manufacturing technique for flexible MEAs with rough gold electrodes suitable for neurotechnology applications.