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With the high flexibility, good conformability and lightweight, the next‐generation energy harvesters could exist in the format of epidermal electronics. They are able to convert the mechanical energy from daily body motions into electrical signals for energy harvesting and human‐machine interfaces. Triboelectric nanogenerators (TENGs) have proven to be excellent candidates for wearable energy harvesters, however, the reported TENGs commonly face the hurdles of poor adhesion to skin and relative thick in geometry up to several cm. Herein, a series of ultrathin, soft, tattoo‐like triboelectric nanogenerators (TL‐TENGs) with well‐designed aesthetic patterns are introduced. With the ultrathin materials applied and state of art processing techniques in epidermal electronics, the TL‐TENGs present an outstanding mechanical property of high robustness and thickness of tens of μm. Besides, TL‐TENGs own remarkable electrical characteristics, the open‐circuit voltage and short circuit current can reach up to ≈180 V and ≈2.2 μA under constant tapping (≈16 kPa), respectively. With the well structural mechanics designs, the TL‐TENGs can be customized into various tattoo patterns, such as twelve Chinese zodiac signs. Demonstrations of TL‐TENGs in energy harvesting and the human‐machine interface indicate great potential in next generation wearable nanogenerators and internet of things. [ABSTRACT FROM AUTHOR]

A class of thin, lightweight, flexible, near-field communication (NFC) devices with ultraminiaturized format is introduced, and systematic investigations of the mechanics, radio frequency characteristics, and materials aspects associated with their optimized construction are presented. These systems allow advantages in mechanical strength, placement versatility, and minimized interfacial stresses compared to other NFC technologies and wearable electronics. Detailed experimental studies and theoretical modeling of the mechanical and electromagnetic properties of these systems establish understanding of the key design considerations. These concepts can apply to many other types of wireless communication systems including biosensors and electronic implants. [ABSTRACT FROM AUTHOR]

Recent advances in flexible electronics have brought great promotions to the next generation of wearable devices, like electronic skin (E-skin). Nevertheless, the powering issue still limits the size, weight and cost for E-skin. Here, trampoline inspired mechanics design and processing techniques in epidermal electronics are combined together to develop a thin, soft, stretchable self-powered tactile sensors based on triboelectric effect for E-skin. With the assistance of microstructure modifying by sandpapers, the TENG sensor exhibits great improved electrical performance and capable of distinguishing a broad range of pressure, with a great sensitivity of 0.367 mV Pa−1. The resulted TENG sensor exhibits excellent stretchability and sensing stability with accurate unchanged signal outputs even under a high-level strain up to 35%. Demonstrations of the sensors associating with the integration with a glove for human-machine interfaces and the development of a 4 × 4 tactile array for pressure mapping and recognition of contact objects, offers great opportunity for next generation self-powered E-skin. ga1 ● Trampoline inspired design in electrode of the TENG sensor for great stretchability. ● TENG-based tactile sensors exhibit great and stable electrical performance under high-level strain. ● E-skin format TENG sensor array for tactile mapping. [ABSTRACT FROM AUTHOR]

Mechanics designs in wearable skin-integrated electronics, also known as epidermal electronics, play an important role in the device performance ranging from flexibility, to robusticity, and to the overall electrical performance. Compared with conventional wearable electronics, self-powered electronics that converting mechanical energy to electricity by using the activities from body's daily motions offers advantages of simple device structures and battery-free characteristics. Here we study a class of mechanics designs that associate with effective working area for stretchable epidermal triboelectric nanogenerators (e-TENGs), and report the relationships between effective working area and the electrical performance of e-TENGs. With the advanced cobweb-serpentine pattern mechanics design, a simple structured, low-cost single-electrode mode e-TENG with open-circuit voltage of ~60 V and a short circuit current output of ~20 μA was achieved. Moreover, the e-TENG's performance is very stable under a broad range of strain values from 0% to 30%. The report of mechanics designs-performance relationships shows a trade-off behavior between the stretchability and the effective working area, which significantly enhances our understanding of mechanics designs for e-TENGs. Image 1 • First report the relationships between effective working area and the electrical performance of epidermal TENGs. • With cobweb-serpentine mechanics design, the relationship between electrical performance and stretchability is evaluated. • By trading-off between performance and stretchability, e-TENG with an optimized design can provide a superior output under up to ~30% strain. • Thin, soft and flexible enough for mounting on skin to harvest energy from daily motion. [ABSTRACT FROM AUTHOR]

Recent advances in thin, soft skin‐integrated electronics have brought many opportunities in the wearable technics. A simple platform with the functionality of self‐powering for epidermal electronics is reported. These electronics can generate electricity from external mechanical stresses that associates with triboelectric effect, and therefore afford excellent performance in tactile sensing and energy harvesting. Combined advances in materials and mechanics of the skin‐integrated electronics with high efficiency energy harvesting techniques, triboelectric nanogenerators (TENGs) in an epidermal format is realized for the first time. The dots‐distributed electrode pattern allows these electronics exhibiting excellent flexibility and stretchability, distinguishing a broad range of pressures that are relevant to normal body motions. The electricity output of the epidermal device from simple finger tapping modes can achieve >60 V of voltage and >1 µA of current, which is sufficient to light up 15 small light‐emitting diodes. Furthermore, the authors also report a 4 × 4 sensor array based on these TENGs, and demonstrate a skin‐like electronics for real‐time motion monitoring and tactile mapping. [ABSTRACT FROM AUTHOR]

U. Paik, J. A. Rogers, and co‐workers present miniaturized flexible electronic systems with wireless power and near‐field communication capabilities on page 4761. The key features are thin, lightweight, flexible construction and minimized interfacial stresses for bio‐integration. These concepts provide new opportunities in biosensors and electronic implants with wireless communication, for use on the fingernails and other regions of the body. [ABSTRACT FROM AUTHOR]