High-density Steeltrodes: A Novel Platform for High Resolution Recording in Primates

Despite recent advances in developing neural probe technologies for rodents using different material platforms, development of neural interfaces for non-human primates (NHP) with high density recording channels and reliable performance remains challenging. The larger brain size in NHPs requires longer probes, making them susceptible to buckling and mechanical failure. While silicon is widely used to implement neural probes for rodents, it is not suitable for NHP probes due to its brittleness and fragility. Here, we demonstrate steeltrode, a high-density neural probe designed for NHPs implemented in stainless steel material with higher durability and larger modulus of resilience compared to silicon probes. Unlike silicon, microfabrication and micromachining of stainless steel has remained mostly unexplored. We discuss two approaches for implementing steeltrodes that consist of a thin high-density Parylene C probe on a stainless steel substrate. In the first approach, the high density Parylene C probe is microfabricated separately and is then affixed to a planar or curved stainless steel shuttle and in the second approach, the high-density probe is monolithically fabricated on stainless steel shuttle by micromachining the stainless steel substrate, a high throughput method for realizing planar probes. In this paper, we will discuss the design, fabrication, characterization and testing of these novel steeltrodes for electrophysiology recording in primates.