Parylene-C Neural Probes with Nanolaminate-sealed and Protruding Electrodes, and In Situ Microactuation

Abstract

Neural probes are a promising tool in understanding the brain, alleviating symptoms of various diseases like Parkinson’s Disease and allowing for applications like controlling prosthetics directly using the mind. However, current probes suffer from deleterious glial tissue buildup, poor insulation and low electrode yield. In this work, to improve upon current probes, ultra-compliant probes are fabricated and integrated with biodissolvable needles. Mechanically compliant probes allow for reduction in the body’s immune response chronically whereas biodissolvable needles provide sufficient stiffness during insertion. To achieve this, contributions are made in the categories of probe design concepts, device level processes, and processes in support of final probe assembly. Major contributions include incorporation of interleaved atomic layer deposited ceramics to create hybrid materials that provide better insulation properties, reducing the distance between the electrode and the site-of-interest by developing a gray scale lithography based technique to fabricate protruding electrodes and creating probes that improve electrode yield by integrating liquid crystal polymers into the parylene-C probe structure, which allows the parylene-C probe to actuate. To allow for integration of the biodissolvable needle with the probe, a peel-based process is developed that controls the adhesion between parylene-C to Si using different HMDS conditions and a transfer based process is developed that enables hightemperature annealing. In addition, a generalized design of neural probes using meandering interconnect structures is developed, allowing for rapid mechanical design of probes. This is key for neural probes because of the application specific nature of neural probe design.