UCLA

There is an increasing need to develop conducting hydrogels for biomedical applications. In particular, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hydrogels have been viewed as optimal materials due to their excellent biocompatibility, stability and softness. However, low-temperature-processable PEDOT:PSS hydrogels, which are needed for biomedical applications have rarely been reported. Such low-temperature processability grant the hydrogels with the capability to in situ engineer the seamless, chronic and strain-free biointerface.

This thesis explores the low-temperature processing of PEDOT:PSS hydrogels for biomedical applications. We first investigated the mechanism for low-temperature and room-temperature gelation of PEDOT:PSS. We demonstrated that by simply injecting the precursor via syringe at room temperature with no additional treatment, the in situ formed PEDOT:PSS hydrogels are highly desirable for minimally invasive biomedical therapeutics with smaller footprints. We found that the room-temperature-formed PEDOT:PSS hydrogels show superior swelling properties after rehydrating, and therefore demonstrated their potential for self‐healing hydrogel electronics. Fiber has favorable structures with ultrahigh aspect ratios that are useful for minimally invasive therapeutics. Advanced by the injectability of PEDOT:PSS hydrogels, we developed a facile strategy for large-scale production of injectable PEDOT:PSS hydrogel fibers at room temperature. As a potential application, we exploited the possibility of using the fabricated PEDOT:PSS hydrogel fibers as channel materials for organic bioelectronic devices, such as organic electrochemical transistors (OECTs), which have been widely used for in vivo bioelectronics studies.