The human body continuously emits physiological and psychological information from head to toe. Wearable electronics capable of noninvasively and accurately digitizing this information without compromising user comfort or mobility have the potential to revolutionize telemedicine, mobile health, and both human–machine or human–metaverse interactions. However, state-of-the-art wearable electronics face limitations regarding wearability and functionality due to the mechanical incompatibility between conventional rigid, planar electronics and soft, curvy human skin surfaces. E-Tattoos, a unique type of wearable electronics, are defined by their ultrathin and skin-soft characteristics, which enable noninvasive and comfortable lamination on human skin surfaces without causing obstruction or even mechanical perception. This review article offers an exhaustive exploration of e-tattoos, accounting for their materials, structures, manufacturing processes, properties, functionalities, applications, and remaining challenges. We begin by summarizing the properties of human skin and their effects on signal transmission across the e-tattoo-skin interface. Following this is a discussion of the materials, structural designs, manufacturing, and skin attachment processes of e-tattoos. We classify e-tattoo functionalities into electrical, mechanical, optical, thermal, and chemical sensing, as well as wound healing and other treatments. After discussing energy harvesting and storage capabilities, we outline strategies for the system integration of wireless e-tattoos. In the end, we offer personal perspectives on the remaining challenges and future opportunities in the field.

中文翻译：

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电子纹身：实现与人体皮肤功能性但难以察觉的交互

人体从头到脚不断地发出生理和心理信息。可穿戴电子产品能够以非侵入性方式准确地数字化这些信息，同时不会影响用户的舒适度或移动性，有可能彻底改变远程医疗、移动健康以及人机或人机交互。然而，由于传统刚性平面电子产品与柔软弯曲的人体皮肤表面之间的机械不兼容性，最先进的可穿戴电子产品在可穿戴性和功能方面面临限制。 E-Tattoos 是一种独特类型的可穿戴电子产品，具有超薄和柔软的特性，可在人体皮肤表面实现无创且舒适的层压，而不会造成阻碍甚至机械感知。这篇评论文章对电子纹身进行了详尽的探索，解释了它们的材料、结构、制造工艺、特性、功能、应用和剩余的挑战。我们首先总结人类皮肤的特性及其对电子纹身-皮肤界面信号传输的影响。接下来讨论电子纹身的材料、结构设计、制造和皮肤附着过程。我们将电子纹身功能分为电气、机械、光学、热和化学传感，以及伤口愈合和其他治疗。在讨论能量收集和存储功能后，我们概述了无线电子纹身的系统集成策略。最后，我们对该领域剩余的挑战和未来的机遇提出了个人观点。