Design Considerations for Improving the Chronic Functionality and Behavioral Outcomes Associated with Intracortical Microelectrode Arrays

Abstract

Implantable recording devices such as intracortical microelectrode arrays can be used to provide bi-directional communication with the nervous system through the recording and stimulation of individual neurons. This enables clinically-relevant applications such as the implementation of brain-machine interfaces which aim to help restore lost motor and sensory functionality to patients with limb loss and paralysis. Their widespread implementation is limited, however, due to an inability to reliably record signals under chronic conditions, likely, in part, stemming from sustained neuroinflammation caused by their implantation. Furthermore, this inflammatory response may also cause unintended cognitive and functional deficits. While the causes of tissue response are multifaceted, mounting evidence suggests that device flexibility and dimensions, as well as neuroinflammation mediated in part by reactive oxygen species may play a large role in these adverse outcomes. In this dissertation, we evaluate design considerations for improving chronic device outcomes and demonstrate: (1) widespread variance in reported chronic study duration and long-term recording performance, as well as a depth-dependent effect on the recording capabilities of planar arrays, (2) the utility of amorphous silicon carbide as an insulator for commercially-available arrays, as well as the substrate for ultrathin arrays in chronic applications, (3) the acute implementation of a synthetic antioxidant coating immobilized onto silicon arrays, and (4) the impact of probe implantation on behavior, motor function, and learning.