Printed microelectrode arrays on soft materials: from PDMS to hydrogels

Microelectrode arrays (MEAs) provide promising opportunities to study electrical signals in neuronal and cardiac cell networks, restore sensory function, or treat disorders of the nervous system. Nevertheless, most of the currently investigated devices rely on silicon or polymer materials, which neither physically mimic nor mechanically match the structure of living tissue, causing inflammatory response or loss of functionality. Here, we present a new method for developing soft MEAs as bioelectronic interfaces. The functional structures are directly deposited on PDMS-, agarose-, and gelatin-based substrates using ink-jet printing as a patterning tool. We demonstrate the versatility of this approach by printing high-resolution carbon MEAs on PDMS and hydrogels. The soft MEAs are used for in vitro extracellular recording of action potentials from cardiomyocyte-like HL-1 cells. Our results represent an important step toward the design of next-generation bioelectronic interfaces in a rapid prototyping approach. Microelectrode arrays: ink-jet printing makes it simpleA cost-effective and simple approach to make soft microelectrode arrays has been developed using inkjet printing of carbon-based conductive ink. Prof Bernhard Wolfrum and his team from the Institute of Bioelectronics (ICS-8) at Forschungszentrum Julich and the Munich School of Bioengineering at Technical University of Munich (TUM), Germany inkjet print functional sensor arrays on various soft substrates for bioelectronic applications. They print carbon nanoparticle conductive ink to fabricate high-resolution microelectrode arrays on PDMS and hydrogels. The soft microelectrode arrays are used for extracellular electrophysiological recordings of action potentials from HL-1 cells. The approach presented in their paper allows for rapid prototyping of disposable sensor array structures on a variety of soft substrates for in vitro as well as in vivo applications.