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) 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.