Abstract

Bioelectronic devices monitor and stimulate biological activity by transducing ionic signals of the body to electronic signals of devices and vice versa. However, their application is limited by a mechanical mismatch between the dry and rigid materials of conventional electronics and the hydrated and soft nature of the body. For implantable devices, this can cause a foreign body response and fibrotic encapsulation of devices. For in vitro devices, differences from native cellular environments can alter cellular activity relative to physiological conditions. To overcome these limitations, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) conducting hydrogels have become a material of interest for creating more tissue-mimetic bioelectronic interfaces. PEDOT:PSS hydrogels are hydrated, soft, and electronically conducting, reducing mechanical mismatch while maintaining bioelectronic functionality. Simultaneously, interconnected microporosity in biomaterials has emerged as a leading structural characteristic for cell infiltration and nutrient transport both in vitro and in vivo as well as tissue integration and vascularization in vivo. Granular hydrogels have attracted considerable attention due to their unique combination of interconnected microporosity and dynamic mechanical properties. Relative to hydrogels with a nano-scale mesh (i.e., bulk hydrogels), granular hydrogels enhance cell infiltration, tissue regeneration, and host vasculature infiltration, and have been explored as encapsulating, conformal, and injectable biointerfaces in a variety of non-conducting biomaterial applications. Because the development of conducting granular hydrogels remains limited, they represent a promising, yet largely unexplored platform for leveraging dynamic mechanical properties and interconnected microporosity at bioelectronic interfaces. In this dissertation, I investigated ionic liquid (IL) as a gelation agent for formation of bulk PEDOT:PSS hydrogels. IL concentration was used to control hydrogel aqueous stability, mechanical properties, and electronic conductivity. Following serum incubation, PEDOT:PSS hydrogels supported primary cells with >95% viability and proliferation over 14 days. Next, I developed methods for generation of PEDOT:PSS microparticles. When densely packed, these microparticles formed a granular hydrogel with interconnected microporosity and dynamic mechanical properties. Modulation of microparticle PSS content achieved enhanced granular hydrogel conductivity, and microparticles showed excellent cytocompatibility (>98% viability). Conducting granular hydrogels demonstrated utility of dynamic mechanical properties and electronic conductivity as bioencapsulating electrodes for electrophysiological monitoring. Finally, I developed methods to stabilize the granular hydrogel and leverage the material’s interconnected microporosity in aqueous environments. Granular hydrogels stabilized with a secondary poly(acrylic acid) (PAA) network possessed a highly interconnected microporous network and further enhanced conductivity (978.5 S m-1). Cells seeded on stabilized granular hydrogels infiltrated the interconnected microporous network, proliferated, and formed homogeneous cellular networks over seven days. Stabilized granular hydrogels were developed into glucose biosensors that detected physiologically relevant glucose concentrations with higher signal-to-noise ratios than bulk PEDOT:PSS hydrogel controls. With further development, these granular hydrogel biosensors could serve as implantable bioelectronics, where the interconnected microporosity promotes tissue integration and vascular infiltration, enhancing interstitial fluid and biomarker transport to the biosensor for enhanced detection.

Committee Chair

Alexandra Rutz

Committee Members

Chuan Wang; Cory Berkland; Srikanth Singamaneni; Yifan Dai

Degree

Doctor of Philosophy (PhD)

Author's Department

Biomedical Engineering

Author's School

McKelvey School of Engineering

Document Type

Dissertation

Date of Award

8-17-2026

Language

English (en)

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Available for download on Saturday, August 14, 2027

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