Skin-inspired wearable self-powered electronic skin with tunable sensitivity for real-time monitoring of sleep quality

In modern times, it is essential to ensure excellent sleep quality and comfort, and a way to scientifically assess these conditions is urgently needed. However, most existing sleep monitoring devices are complicated and uncomfortable to wear. Here, a dermal papillae-bioinspired self-powered multifunctional electronic skin (e-skin) with an all-fibrous multilayer nanostructure based on a triboelectric nanogenerator is proposed, which is sensitive, lightweight, ultrathin, breathable, biocompatible, and low-cost. Owing to the bead polyvinylidene fluoride nanofibers of the e-skin simulating the dermal papillae of natural skin and the N-(2-aminoethyl)-3-aminopropyl trimethoxy silane-modified nature of the collagen aggregate nanofibers, the e-skin exhibits the highest sensitivity (0.32 V kPa(-1)) in the range of 0-135 kPa. Additionally, it has short response and recovery times (20 and 33 s, respectively) in the humidity range of 25-85% RH. More importantly, the e-skin converts mechanical energy into electrical energy for humidity detection via an energy circulation system. The e-skin can collect the heartbeat and respiration signals and perform an analysis on their frequency and stability, which can be used to accurately measure the different sleep phases. By analyzing the proportion of each phase and environmental humidity, the e-skin can be employed to scientifically assess the sleep quality and comfort of insomnia patients and night owls through real-time monitoring.