Stimuli-Responsive Conductive Hydrogels

Electronically-conductive hydrogels, composites of crosslinked and water-swollen polymers with a conducting material (polymer or inorganic nanoparticles) can address the mechanical and electronic mismatch between electronic devices and biological systems. While several methods have been reported to prepare these conductive hydrogels, several issues have to be addressed to enable their translation in bioelectronics. These issues include: (1) the increase in elastic modulus at high loading of conducting material, (2) the irreversibility of the gelation mechanism, which complicates the delivery and potential removal of the conductive hydrogel in vivo, and (3) the difficulty in controlling the micro- and macro-structure of the conductive hydrogels for applications in tissue engineering and wearable electronics. In this talk, I will share our progress towards addressing these issues through the use of synthetic chemistry, particularly using novel stimuli-responsive conducting polymers. In the first part, I will discuss the use of thermo-responsive conducting polymers that displays a reversible sol-gel transition close to body temperature, thereby enabling injectable conductive hydrogels. The second part will be focused on achieving spatiotemporal control by using photo-active polymers to simultaneously photo-catalyze the polymerization of a conducting polymer and photo-crosslink its supporting matrix. This approach has great potential for 3D printing conductive hydrogels with a controlled microstructure and high resolution using light.