Ultra-Tough, highly stable and Self-Adhesive Goatskin-Based intelligent Multi-Functional organogel e-skin as Temperature, Humidity, Strain, and bioelectric four-mode sensors for health monitoring

The rapid development of intelligent electronics has facilitated the transition of electronic devices from rigid systems to flexible ones. Flexible electronic skin (E-skin) that mimics natural biologic skin has attracted widespread attention owing to its significant applications in health management, soft robotics, human-machine interaction, etc. However, the increasing demand for more advanced functionalities imposes higher requirements on E-skin, such as high mechanical strength, flexibility, and biocompatibility. Herein, a top-down strategy was adopted to prepare a multifunctional organogel-based E-skin by using flexible but tough goatskin as the basic framework followed by the filling treatment with a poly(methacrylic acid-acrylamide) (P(MAA-co-AM)) network. This organogel exhibited excellent mechanical strength and puncture resistance, with fracture stress of 3.86 MPa and breaking elongation of 230 %, respectively, thus serving as the second skin layer to protect human body. Unlike conventional water-containing hydrogels, this organogel possessed exceptional biocompatibility and environmental stability, enabling it to operate normally at low temperature (e.g. -20 C-degrees) and after long-term storage (> 15 d). More importantly, the crucial properties for practical application, such as adhesion, conductivity, and antibacterial performance, have been integrated into this organogel. A flexible, stretchable, and durable organogel-based sensor was further developed that can accurately monitor large-scale movements and subtle physiological signals of human body within a wide range of temperature and duration. Moreover, it could simultaneously achieve temperature, humidity, strain, and bioelectricity responsiveness on the same platform. This four-mode sensing mechanism can effectively complement and calibrate human body's health data, thus realizing precise monitoring of human health conditions. This work provides a new approach to structural design, enhancement, and multifunctionality of intelligent E-skin, aiming to replicate or even surpass the performance of real animal skin.