Biocompatible neural electrodes and polymeric interface studies

Thesis

Over the last two decades, biomaterials have gained significant attention due to their versatility and practicality in biomedical applications. Polymers such as polydimethylsiloxane (PDMS) and poly(3,4-ethylenedioxythiophene) (PEDOT) have been extensively utilized, driving advancements in fields such as tissue engineering, drug delivery, and neural implants. This thesis investigates biocompatible materials for neural electrodes and the interactions at polymeric interfaces. The studies presented follow a general logic: it begins by understanding the basics of materials, advances to exploring their properties and functionalities, and concludes with in vivo studies.

Chapter 1 includes an overview of fundamental principles in neuroscience, electrochemistry, and mechanics, followed by an introduction to experimental tools such as cyclic voltammetry (CV), chronoamperometry, and atomic force microscopy (AFM) (Chapter 2). These foundational chapters provide the basis for the methodologies employed in subsequent material characterizations.

Chapter 3 investigates the mechanical properties of PDMS over time using AFM, revealing surface changes under different conditions. These findings emphasize the importance of monitoring interface properties for long-term applications. Chapters 4 and 5 focus on PEDOT with different dopants (PSS^- and Cl^-), detailing the optimization of coating techniques using electropolymerization. Surface morphology analysis via AFM and electrochemical studies were conducted to ensure the production of stable, isolated coatings suitable for neural electrodes.

Building on these characterizations, Chapter 6 describes in vitro experiments to study ionic motion at the polymer-solution interface using a biopotentiostat setup mimicking neural activity. Chapter 7 advances to in vivo studies by implanting PEDOT-coated tetrodes into a mouse brain, demonstrating the device biocompatibility and evaluating its neural recording performance.

Overall, the thesis establishes a solid understanding of biomaterials PDMS and PEDOT, revealing insights into polymer surface alterations, ionic response dynamics, and coating optimization for neural electrodes. Together, these results can be instrumental in the further development of neural recording devices.

Authors: Zhang, Y

• DOI: 10.5287/ora-1ag49jzv9
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Biophysics