Thin-film Electrode Arrays
NeuroNexus arrays are manufactured using state-of-the-art design, microfabrication and packaging techniques employed in the semiconductor and MEMS industries. Design is accomplished using a computer-aided design (CAD) tool that results in a multilayer mask set. These masks are used in the fabrication process to photolithographically transfer patterns of the probe features onto thin-films (< 1 µm) that have been deposited on a silicon wafer. Subsequent etching, thin-film deposition and lithography steps are then used to build up the layered structure. Once complete, the arrays are released from the wafer and are ready for assembly, testing and final QC.
The process starts with a substrate that provides structural support. A thin-film dielectric is next deposited to provide insulation and perhaps more structural support to the lead material which is next deposited and patterned to form individual interconnects for signal transduction. These are capped off by a top thin-film layer of dielectric, through which vias are opened to provide contact to the underlying leads. Metal is next deposited, patterned and etched to form the bond pads and electrode sites. The materials used to form the arrays are selected for their biocompatibility and functionality in an implantable array.
Probe fabrication is a batch process that allows us to fabricate a variety of designs simultaneously on a silicon wafer. Resulting devices have conductive traces that are 1 µm or less. Final thickness is typically 15 or 50 µm (silicon) or 12 µm (polyimide), but can be customized depending on the application. Layout of the electrode sites and shanks can be customized to fit your specific experimental needs.
NeuroNexus offers two base technology platforms that have differing mechanical properties: silicon and polyimide. Silicon arrays are more rigid and are therefore used for penetrating tissue in structures including brain, spinal cord, peripheral nerve and the heart. Polyimide is flexible and is used for producing surface arrays such as ECoGs, EEGs and cuffs for use on brain, scalp, peripheral nerve and the heart.