Shielding of flexible microelectrode interconnects for suppression of artifacts in neural prostheses

An approach for the suppression of artifacts in interconnects of neural prostheses is described. Micromachining technologies have been applied to develop flexible multichannel electrodes with integrated interconnects. Often, electrodes were implanted on nerves with large muscles nearby. Artifacts from muscle activity could couple into the interconnect lines and disturb the small signals recorded from nerves. Therefore, we present a new generation of flexible electrodes with an electrical shielding of the interconnects. Simulations with a discrete cable model of the microdevices were performed. Additionally, a setup for in vitro measurements of interconnect properties in a physiologic environment was built up. Measurements of crosstalk between the lines and coupling of external signals were performed and compared with the simulations. Shielded interconnects as well as unshielded ones showed only small crosstalk between the lines in a physiologic saline solution. The coupling of an external potential ("artifact") into the interconnects could be reduced by 50% when the electrical shield was put to ground potential.