UV Laser-Induced Carbon Microelectrode Arrays for Neuronal Recordings

Bioelectronic devices for in vitro and in vivo studies benefit from polymeric materials as substrates and insulations due to their flexible nature. Laser-induced carbon formation has emerged as a rapid and versatile technique to fabricate conductive carbon-based structures from insulating polymer films. Here, the development of electrodes fabricated via ultraviolet (UV) laser-induced carbonization of chlorinated poly-p-xylylene (parylene-C) insulation areas is reported. The parylene-derived carbon is directly fabricated over the thin metallization layer, thus opening the desired electrode areas in a one-step process. The optimal laser parameters for electrode performance are investigated, and the stability of the electrodes is tested under 10 000 voltage-controlled stimulation pulses. In vitro tests of primary neuronal cultures confirm the biocompatibility of the proposed interfaces and reveal the good conformability of the neurons over the rough carbon structures. The performance of the sensor arrays is shown in electrophysiological recordings of neuronal cultures, together with a proof-of-principle stimulation, confirming the stability of the recordings over at least 4 weeks in culture. The proposed laser-induced carbon electrodes from polymer coating are suitable as a rapid and precise fabrication protocol for carbon-based sensors, applicable to bioelectronics and neuroelectronics devices.