Due to the fact that roughly sixty percent of the human body is essentially composed of water, the human body is inherently a conductive object, being able to, firstly, form an inherent electric field from the body to the surroundings and secondly, deform the distribution of an existing electric field near the body. Body-area capacitive sensing, also called body-area electric field sensing, is becoming a promising alternative for wearable devices to accomplish certain tasks in human activity recognition and human-computer interaction. Over the last decade, researchers have explored plentiful novel sensing systems backed by the body-area electric field. On the other hand, despite the pervasive exploration of the body-area electric field, a comprehensive survey does not exist for an enlightening guideline. Moreover, the various hardware implementations, applied algorithms, and targeted applications result in a challenging task to achieve a systematic overview of the subject. This paper aims to fill in the gap by comprehensively summarizing the existing works on body-area capacitive sensing so that researchers can have a better view of the current exploration status. To this end, we first sorted the explorations into three domains according to the involved body forms: body-part electric field, whole-body electric field, and body-to-body electric field, and enumerated the state-of-art works in the domains with a detailed survey of the backed sensing tricks and targeted applications. We then summarized the three types of sensing frontends in circuit design, which is the most critical part in body-area capacitive sensing, and analyzed the data processing pipeline categorized into three kinds of approaches. Finally, we described the challenges and outlooks of body-area electric sensing.

翻译：由于人体约百分之六十由水构成，人体本质上是一种导电物体，既能从身体向周围环境形成固有电场，又能改变身体附近现有电场的分布。人体区域电容感应（亦称为人体区域电场感应）正成为可穿戴设备在人类活动识别与人机交互中完成特定任务的一种有前景的替代方案。过去十年间，研究人员已探索了大量基于人体区域电场的新型传感系统。然而，尽管人体区域电场研究广泛，目前尚无全面综述提供启发性指导。此外，不同的硬件实现、应用算法和目标应用使得对该领域进行系统性概述颇具挑战。本文旨在通过全面总结现有的人体区域电容感应研究成果弥补这一空白，使研究者能够更清晰地把握当前探索现状。为此，我们首先根据涉及的身体形态将探索分为三个领域：身体部位电场、全身电场和身体间电场，并详细列举了这些领域内的前沿工作，同时深入梳理了其支撑传感原理与目标应用。随后，我们总结了电路设计中三类传感前端——这是人体区域电容感应的关键部分，并分析了分为三种类型的数据处理流程。最后，我们阐述了人体区域电场感应的挑战与展望。