Fully Printed μ-Needle Electrode Array from Conductive Polymer Ink for Bioelectronic Applications

Microelectrode arrays (MEAs) are widely used platforms in bioelectronicsto study electrogenic cells. In recent years, the processing of conductive polymers for the fabrication of three-dimensional electrode arrayshas gained increasing interest for the development of novel sensor designs. Here, additive manufacturingtechniques are promising tools for the production of MEAs with three-dimensional electrodes. In this work, a facile additive manufacturing process for the fabrication of MEAs that feature needle-like electrode tips, so-called μ-needles, is presented. To this end, an aerosol-jet compatible PEDOT:PSSand multiwalled carbon nanotube composite ink with a conductivity of 323 ± 75 S m–1 is developed and used in a combined inkjet and aerosol-jet printing process to produce the μ-needle electrode features. The μ-needles are fabricated with a diameter of 10 ± 2 μm and a height of 33 ± 4 μm. They penetrate an inkjet-printed dielectric layer to a height of 12 ± 3 μm. After successful printing, the elec...