Microfabrication of ultra-long reinforced silicon neural electrodes

The authors describe a simple dry-etch silicon microfabrication process to develop an array of electrodes with multiple recording sites suitable for neural recording applications. This new high-yield fabrication process uses commercially available ultra-thin silicon wafers as substrate material. A xenon difluoride system is used to etch the silicon substrate to form the electrode structures. The novel concept of structural reinforcement to produce elongated and reliable probe electrodes is introduced. The authors demonstrate recording silicon electrodes that can reach lengths longer than 10 mm having only 50 µm thicknesses and an 100 µm average width. This new microfabrication process illustrates a simple, cost-effective and mass-producible method for developing ultra-long silicon probes for deep brain implantation and neural recording.