Radical Polymer-based Mixed Conductors and Their Application to Bioelectronic Ocular Sensors

Optoelectronically active polymers have made critical inroads in many solid-state electronic devices (e.g., organic field-effect transistors), and excitingly, macromolecules capable of providing mixed electronic and ionic conduction offer unique opportunities in many application areas including bioelectronic devices. Here, we first describe how a blend of a common conjugated polymer, poly(3-hexylthiophene) (P3HT), and a radical polymer (i.e., a macromolecule with a nonconjugated backbone and with stable open-shell sites on its pendant groups), poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO), allows for the creation of high-performance organic electrochemical transistors (OECTs) through a unique mixed conduction mechanism where the phase separation of the thin film polymer blend allows for discrete transport regimes between the conjugated polymer and radical polymer phases. Second, we will discuss how this type of archetype can be translated to biomedical device applications through a practical demonstration of a stretchable and flexible polymer-based biosensor. This bioelectronic device is inkjet-printed atop a commercial soft contact lens in a high-throughput manner, and our electroretinogram (ERG) sensor shows performance that is superior to current clinical gold standards in human subjects. In this way, we couple the physics of the polymer system to translational performance to demonstrate clear patient impact.