Ultra stretchable, tough, elastic and transparent hydrogel skins integrated with intelligent sensing functions enabled by machine learning algorithms

Hydrogel-based ionic skins are ionic conductive artificial skin-like materials that are promising for a broad range of applications such as wearable sensory devices, soft robotics and machines, and bioelectronics. However, fabricating hydrogel skins with satisfying mechanical performance and intelligent sensing functions is still a significant challenge. Herein, we have developed an ionic conductive nanocomposite hydrogel with ultra stretchability and self-evolving sensing functions. By leveraging the dynamic feature of synergetic interfacial ionic interactions, a trace amount of carbon nanotubes endows the hydrogel networks with excellent mechanical performances (i.e., tensile strength, stretchability and toughness up to 1.09 MPa, 4075 % and 12.8 MJ/m3, respectively). Additionally, the hydrogel is soft, elastic, transparent and self-healing. The rational combination of the mechanical and electrical properties renders the as-prepared hydrogel with excellent sensing performances and cycling stability, and therefore enables it to perform as a sensory unit of a complete platform for the recognition of some complicated human behaviors, outperforming the previously reported hydrogels due to its intelligent sensing functions. Specifically, with the integration of machine learning module, the hydrogel-based platform exhibits great recognition accuracies to human handwriting motions from single letters to words, phrases, and short sentences after proper training. The combination of superior mechanical performances and self-evolving sensing functions within this hydrogel-based ionic skin unlocks its potential as the intelligent human-device interface, which promotes the application of artificial intelligence in customized electronic devices.