A Robust and Adhesive Hydrogel Enables Interfacial Coupling for Continuous Temperature Monitoring

摘要

Continuous temperature monitoring by flexible hydrogel-based electronicsachieves rapid advances, overcoming the drawbacks of rigid and unportablethermocouples. However, an open question is whether and how thethermosensitive hydrogel designing can prevent mechanical mismatchingbetween devices and skin-tissues and reduces interfacial failure. Herein,a versatile hydrogel-based thermistor epidermal sensor (HTES) paradigmis engineered consisting of thermosensitive and self-adhesive functionlayer (PEST) in tandem with a surface spraying Ag interdigital electrode.Leveraging the advantage of catechol chemistry inspired tannic acidcoatedcellulose nanocrystals, the resultant PEST achieves the adhesioncohesionequilibrium along with superior thermosensitivity. The assembledHTES thereby yields unprecedented features of superior thermosensitivity(TCR = 1.43 ℃~(?1)), exceptional mechanical integrity (hammering200 cycles, current variation <9), impressive interfacial compatibility(adhesion strength, 25 kPa), and environmental stability (thermosensationretention of 98 over 5 days). By in-situ microstructure observation, theunique geometrical synchronization of HTES with arbitrary curvilinear surfaces(e.g., sphere, cone, and saddle) stemming from elastic dissipation anddiscrete rupture of the adhesive fibrillar bridges is validated, affording competitiveadvantages than that of the state-of-the-art thermistor electronicsfor alleviating the interfacial deterioration, which dramatically inspiresadvanced HTES design strategies and paves the way for commercializationof attachable thermistor electronics.