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.