Multifunctional flexible polymer-based intracortical neural recording microelectrodes.

Abstract

In neuroscience, understanding the complex functionality of the brain as an electrochemical system requires the ability to deliver precise amounts of chemicals to localized areas while monitoring the cellular electrical feedback responses in vivo. In clinical medicine, the treatment of certain neurodegenerative disorders may be facilitated by the local chronic delivery of neurotrophic agents. Therefore, drug infusion via a chronic, flexible hybrid neural recording electrode with controlled chemical delivery capabilities constitutes a critical enabling technology in neurological science and medicine. This dissertation outlines the research and development of a novel, flexible polymer-based, hybrid multi-site neural recording BIO-MEMS interface with microfluidic drug delivery capabilities to be used for delivery of chemicals to the central nervous system. The devices were surface micro-machined out of polymers and thin film metals on 100 mm silicon carrier wafers using a CMOS compatible process in the class 100 clean room environment of the Center for Solid State electronics (CSSER) at Arizona State University and the Solid State Electronics Lab (SSEL) at the University of Michigan. Various polymers including polyimide and parylene-C were used to fabricate electrode prototypes. The noteworthy outcomes of this work start with the development of polyimide-based passive intracortical neural recording microelectrodes with bioactive capabilities that were shown to be capable of recording multisite neural activity. After gaining more experience in the characteristics of polymers and polymer processing, I switched to parylene substrates because they offer better prospects for long term viability. This resulted in the significant development of parylene-based microelectrodes that demonstrated the ability to deliver nanoliter quantities of fluid to localized areas, while also showing the ability to record multisite unit activity. These results suggest that the polymer-based electrodes resulting from this work can push the current limitations of CNS recordings toward a permanent, polymer-based microscale neural interface.