An integrated self-healable electronic skin system fabricated via dynamic reconstruction of a nanostructured conducting network.

Electronic skin devices capable of monitoring physiological signals and displaying feedback information through closed-loop communication between the user and electronics are being considered for next-generation wearables and the 'Internet of Things'. Such devices need to be ultrathin to achieve seamless and conformal contact with the human body, to accommodate strains from repeated movement and to be comfortable to wear. Recently, self-healing chemistry has driven important advances in deformable and reconfigurable electronics, particularly with self-healable electrodes as the key enabler. Unlike polymer substrates with self-healable dynamic nature, the disrupted conducting network is unable to recover its stretchability after damage. Here, we report the observation of self-reconstruction of conducting nanostructures when in contact with a dynamically crosslinked polymer network. This, combined with the self-bonding property of self-healing polymer, allowed subsequent heterogeneous multi-component device integration of interconnects, sensors and light-emitting devices into a single multi-functional system. This first autonomous self-healable and stretchable multi-component electronic skin paves the way for future robust electronics.

Investigating Limiting Factors in Stretchable All-Carbon Transistors for Reliable Stretchable Electronics.

Stretchable form factors enable electronic devices to conform to irregular 3D structures, including soft and moving entities. Intrinsically stretchable devices have potential advantages of high surface coverage of active devices, improved durability, and reduced processing costs. This work describes intrinsically stretchable transistors composed of single-walled carbon nanotube (SWNT) electrodes and semiconductors and a dielectric that consists of a nonpolar elastomer. The use of a nonpolar elastomer dielectric enabled hysteresis-free device characteristics. Compared to devices on SiO2 dielectrics, stretchable devices with nonpolar dielectrics showed lower mobility in ambient conditions because of the absence of doping from water. The effect of a SWNT band gap on device characteristics was investigated by using different SWNT sources as the semiconductor. Large-band-gap SWNTs exhibited trap-limited behavior caused by the low capacitance of the dielectric. In contrast, high-current devices based on SWNTs with smaller band gaps were more limited by contact resistance. Of the tested SWNT sources, SWNTs with a maximum diameter of 1.5 nm performed the best, with a mobility of 15.4 cm2/Vs and an on/off ratio >103 for stretchable transistors. Large-band-gap devices showed increased sensitivity to strain because of a pronounced dependence on the dielectric thickness, whereas contact-limited devices showed substantially less strain dependence.