A Breathable, Stretchable, and Self-Calibrated Multimodal Electronic Skin Based on Hydrogel Microstructures for Wireless Wearables

Biomimetic electronic skins (e-skins) are widely used in wearables, smart prosthesis and soft robotics. However, multimodal e-skins, especially those based on hydrogels, face multiple challenges for practical applications, involving multi-sensing signal mutual interference, low breathability and stretchability. Here, a breathable and stretchable multimodal e-skin with a multilayer film microstructure is developed to achieve self-calibrated sensing of any two of three stimuli: strain, temperature, and humidity, with minimal crosstalk. Hydrogel fibers with different shapes are designed for strain and temperature sensing modules, and the hydrogel film is developed as a humidity sensing module. The multimodal e-skin exhibits impressive sensing performance, including a low strain detection limit (0.03%), strain linearity (R² = 0.990), high-temperature sensitivity (1.77%/°C), and a wide humidity detection range (33–98% RH). Interestingly, due to the directional anisotropy in strain sensitivity of different shaped fibers, the e-skin realizes self-calibrated detection of strain and temperature in different directions. By introducing porous elastomer encapsulation membranes, the breathability and wearing comfort of the e-skin are attained, while the high stretchability (100% strain) is maintained. Furthermore, a personalized human-machine interaction system is created by integrating the e-skin with a wireless circuit to realize real-time and wireless gesture recognition, physiological signals monitoring, and smart prosthesis.