Multifunctional carbon nanotube hydrogels with on-demand removability for wearable electronics

Wearable electronics that can convert various external stimuli into electrical signals hold great potential for diverse applications. Efforts in this area are focused on developing functional hydrogels to improve the values of these flexible electronics. Herein, we present a novel carbon nanotube (CNT)-based hydrogel with the synergistic features of good mechanical strength, high sensitivity, self-healing capability, and on-demand removability for wearable electronics. The hydrogel was fabricated by mixing dopamine-modified oxidized hyaluronic acid (OHADA), cyanoacetate group-functionalized dextran (DEX-CA), and carbon nanotubes (CNTs) in the presence of histidine. The catechol and aldehyde groups on OHA-DA impart the hydrogel with high tissue adhesiveness. Owing to the existence of CNTs, the hydrogel exhibited outstanding conductivity and could respond to different human motions and convert these stimuli as resistance signals. Notably, because of the photothermal conversion property of CNTs and thermally reversible performance of the generated C=C double bonds between aldehyde groups and cyanoacetate groups, the hydrogel was imparted with intriguing on-demand dissolution ability under near-infrared (NIR) irradiation and could be facilely removed from tissues whenever necessary. We believe that such hydrogel will open up new opportunities for the design and construction of next-generation wearable electronics.