Nanomaterial-modified Flexible Micro-electrode Array by Electrophoretic Deposition of Carbon Nanotubes

Micro-electrode arrays (MEAs) and micro-electrodes are used in a variety of medical applications for recording action potentials or stimulating neurons. To have an excellent signal-to-noise ratio, the contact between the neuronal tissue and the micro-electrodes must be very close. Therefore, a flexible MEA with a large number of electrodes on a large area is necessary. In this work, a flexible micro-electrode array (MEA) with an integrated flexible CMOS-chip was designed and fabricated. By connecting several of these MEAs by a bus system, the number of electrodes and therefore the spatial resolution can be increased extremely. Because of the small size of the micro-electrodes (<120 μm) each electrode needs a high charge delivery capacity and a high “true” surface area for stimulation, respectively. This can be obtained by coating the electrodes by disordered multi-walled carbon nanotubes (MWCNTs). Direct current pulsed Electrophoretic Deposition (EPD) has been proved successfully for the aforementioned application. The effective deposition time and the pulse width were figured out to create ideal MWCNT-electrode properties, particularly, with regard to the enhancement of the “true” surface area, microscopic homogeneity and reproducibility of the layer.