Room-temperature self-healing piezoresistive sensors

Skin-inspired materials facilitate the design and fabrication of various biomedical devices capable of real-time monitoring of physiological signals and provide the foundations for mechanically compliant next-generation wearables that behave and operate like an extension of our own integumentary system. These devices need to maintain conformal contact with the body while offering very little mechanical impedance and must be able to sustain the accidental damage that comes in normal, dynamic, everyday life. This work demonstrates how dynamic metal-ligand self-healing chemistry can be used to synthesize multi-wall carbon nanotubes (MWCNT) – silicone nanocomposites with skin-like mechanical elasticity. Highly repeatable, room-temperature self-healing nanocomposites were synthesized with various filler concentrations to study the ability of the material to perform in sensing and electronic interconnect scenarios. An increase in mechanical stiffness from 8 kPa to 102 kPa were achieved at a percolation of 4.8 %wt, maintaining extensibility up to 50%. Further, conductivities as high as 2 × 10−2 S/m were achieved whilst maintaining high flexibility, offering tuneability for a broad range of tailored applications. The gauge factor (GF) performance was independent of healing cycles, maintaining a value of 1.4 after several ruptures, and continually sustains mechanical stiffness matching the dermal layer of the human forearm. These results parallel the human skin's ability to both heal damage elements and respond to stimuli of the world around us and provide expandability to current biomedical systems.