Comparison of the in-vivo neural recording quality of floating and skull-fixed silicon probes

Silicon neural probes with sophisticated integrated CMOS-based electronics providing a large number of recording sites integrated along the slender probe shanks have become a driving force in neural engineering throughout the past decade. Using such neural probes in a chronic setting often requires to mechanically anchor them with respect to the skull. Any relative motion between brain and implant causes however tissue responses such as glial scarring, thereby the recordable neurons are shielded from the electrodes integrated on the probe, and the signal quality is decreased. In the current work, we present preliminary results obtained using a mechanically fixed and a floating silicon neural probe implanted into the cortex of a non-human primate. We demonstrate that the neural signal quality of the floating probe is superior to the fixed approach. Nonetheless, also the skull-fixed probe allowed to identify action potentials and stably record low frequency signals over the entire recording period.