A non-faradaic junction (NFJ) is a connection between an ionic conductor and an electronic conductor in which no electrochemical reaction takes place. The junction behaves like a capacitor and couples the ionic and electronic currents through chemistry, electricity and entropy. Its charge–voltage curve is sensitive to various environmental signals, allowing it to function as a sensor; because no reaction occurs, the sensing is non-destructive and long-lasting. NFJ sensors have high sensitivity, rapid response and small size, and they can be self-powered. These sensors are familiarly used in electrophysiology of the heart, brain and muscles, and applications are emerging in wearable and implantable devices and soft robotics, as well as in sensing pressure, sound, temperature and chemicals. In this Review, we discuss NFJ sensors, emphasizing the development of devices and materials for each side of the junction. The flexibility in choosing materials enables NFJ sensors to fulfil challenging requirements, such as softness, stretchability, transparency and degradability.

非法拉第结 （NFJ） 是离子导体和电子导体之间的连接，其中不发生电化学反应。结的作用类似于电容器，通过化学、电和熵耦合离子和电子电流。其电荷-电压曲线对各种环境信号敏感，使其能够用作传感器;由于没有发生反应，因此传感是非破坏性的且持久的。NFJ 传感器灵敏度高、响应快、体积小，并且可以自供电。这些传感器广泛用于心脏、大脑和肌肉的电生理学，并且正在应用于可穿戴和植入设备、软机器人技术，以及传感压力、声音、温度和化学品。在这篇综述中，我们讨论了 NFJ 传感器，强调了结点两侧的器件和材料的开发。NFJ 传感器在材料选择方面的灵活性使其能够满足具有挑战性的要求，例如柔软性、可拉伸性、透明度和可降解性。