n-Type Conjugated Polymers for Organic Bioelectronics and Point-of-Care Applications

Abstract

Quick and early detection of abnormalities in the body's metabolism is of paramount importance to monitor, control, and prevent the associated diseases and pathologies. Biosensors technology is rapidly advancing, from the first electronic biosensor reported by Clark and Lyons in 1962 for blood glucose monitoring to today’s devices that can detect multiple metabolites in bodily fluids continuously and simultaneously within seconds. This rapid growth in point-of-care devices promises for the development of novel devices with different form factors and the ability to detect a wide range of biomarkers. These advancements mainly stem from the development of electronic materials that have properties better aligning with the biotic interface compared to the traditional metal electrodes. A promising class of electronic materials for biosensors is conjugated polymers. Conjugated polymers are carbon-based, organic semiconducting materials made of long chains comprising conjugated repeat units. The fundamental property that makes these materials so attractive is, however, not their electronic conductivity, but their ionic conductivity. As living organisms use ionic fluxes to relay signals, materials that can conduct ionic currents are believed to facilitate the communication between the electronics and living systems. This communication happens at various levels: organs, complex tissues, cells, cell membrane, proteins, and small biomolecules. Besides, the inherently soft nature of these materials facilitates mechanical conformity with soft biological systems. The field of organic bioelectronics has experienced tremendous growth over the past two decades, thanks to the design of new conjugated polymers customized for the biotic interface. While hole conducting (p-type) polymers have been widely investigated, electron conducting (n-type) counterparts are relatively new. This dissertation aims to explore the capabilities of n-type conjugated polymers for bioelectronics applications. Chapter 1 overviews the key properties of conjugated polymers and the resulting electronic devices that leverage these properties for specific applications in bioelectronics. Chapter 2 presents microfabricated metabolite (lactate and glucose) sensors based on an n-type polymer in combination with enzymes, and how this communication can enable energy production from bodily fluids. Finally, Chapter 3 reports the development of engineering and design strategies to enhance the performances of n-type polymers in bioelectronics.