Browsing by Author "Guo, Tianzheng"
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Item Electronically Conductive Hydrogels by in Situ Polymerization of a Water-Soluble EDOT-Derived Monomer(Advanced Engineering Materials, 2022-05-13) Nguyen, Dan My; Wu, Yuhang; Nolin, Abigail; Lo, Chun-Yuan; Guo, Tianzheng; Dhong, Charles; Martin, David C.; Kayser, Laure V.Electronically conductive hydrogels have gained popularity in bioelectronic interfaces because their mechanical properties are similar to biological tissues, potentially preventing scaring in implanted electronics. Hydrogels have low elastic moduli, due to their high water content, which facilitates their integration with biological tissues. To achieve electronically conductive hydrogels, however, requires the integration of conducting polymers or nanoparticles. These “hard” components increase the elastic modulus of the hydrogel, removing their desirable compatibility with biological tissues, or lead to the heterogeneous distribution of the conductive material in the hydrogel scaffold. A general strategy to transform hydrogels into electronically conductive hydrogels without affecting the mechanical properties of the parent hydrogel is still lacking. Herein, a two-step method is reported for imparting conductivity to a range of different hydrogels by in-situ polymerization of a water-soluble and neutral conducting polymer precursor: 3,4–ethylenedioxythiophene diethylene glycol (EDOT-DEG). The resulting conductive hydrogels are homogenous, have conductivities around 0.3 S m−1, low impedance, and maintain an elastic modulus of 5–15 kPa, which is similar to the preformed hydrogel. The simple preparation and desirable properties of the conductive hydrogels are likely to lead to new materials and applications in tissue engineering, neural interfaces, biosensors, and electrostimulation.Item One Pot Photomediated Formation of Electrically Conductive Hydrogels(ACS Polymers Au, 2024-02-14) Nguyen, Dan My; Lo, Chun-Yuan; Guo, Tianzheng; Choi, Taewook; Sundar, Shalini; Swain, Zachary; Wu, Yuhang; Dhong, Charles; Kayser, Laure V.Electrically conductive hydrogels represent an innovative platform for the development of bioelectronic devices. While photolithography technologies have enabled the fabrication of complex architectures with high resolution, photoprinting conductive hydrogels is still a challenging task because the conductive polymer absorbs light which can outcompete photopolymerization of the insulating scaffold. In this study, we introduce an approach to synthesizing conductive hydrogels in one step. Our approach combines the simultaneous photo-cross-linking of a polymeric scaffold and the polymerization of 3,4-ethylene dioxythiophene (EDOT), without additional photocatalysts. This process involves the copolymerization of photo-cross-linkable coumarin-containing monomers with sodium styrenesulfonate to produce a water-soluble poly(styrenesulfonate-co-coumarin acrylate) (P(SS-co-CoumAc)) copolymer. Our findings reveal that optimizing the [SS]:[CoumAc] ratio at 100:5 results in hydrogels with the strain at break up to 16%. This mechanical resilience is coupled with an electronic conductivity of 9.2 S m–1 suitable for wearable electronics. Furthermore, the conductive hydrogels can be photopatterned to achieve micrometer-sized structures with high resolution. The photo-cross-linked hydrogels are used as electrodes to record stable and reliable surface electromyography (sEMG) signals. These novel photo-cross-linkable polymers combined with one-pot PEDOT (poly-EDOT) polymerization open possibilities for rapidly prototyping complex bioelectronic devices and creating custom-designed interfaces between electronics and biological systems.