Dry electrodes are a promising solution for prolonged EEG signal acquisition, whereas wet electrodes may lose their signal quality in the same situation and require skin preparation for set-up. Here, we review the impedance and noise of passive and active dry EEG electrodes. In addition, we compare noise and input impedance of the EEG amplifiers. As there are multiple definitions of impedance in each EEG system, they are all first defined. Electrodes must be compatible with amplifiers to accurately record EEG signals. This implies that their impedance plays a significant role in amplifier compatibility and affects total input-referred noise. Therefore, we review the impedance and noise of state-of-the-art amplifiers and electrodes. Furthermore, we compare the various structures and materials used and their final impedance to that of wet electrodes. Finally, we compare state-of-the-art electrodes and amplifiers to the standards of the IFCN and IEC80601-2-26. We investigate bottlenecks and propose a guideline for future work on passive and active dry electrodes, as well as EEG amplifiers.

中文翻译：

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无源和有源干式 EEG 电极的阻抗和噪声：综述

干电极是延长 EEG 信号采集时间的有前途的解决方案，而湿电极在相同情况下可能会失去其信号质量，并且需要皮肤准备进行设置。在这里，我们回顾了被动和主动干 EEG 电极的阻抗和噪声。此外，我们还比较了 EEG 放大器的噪声和输入阻抗。由于每个 EEG 系统中都有多种阻抗定义，因此首先对其进行定义。电极必须与放大器兼容才能准确记录 EEG 信号。这意味着它们的阻抗在放大器兼容性方面起着重要作用，并影响总输入参考噪声。因此，我们回顾了最先进的放大器和电极的阻抗和噪声。此外，我们将使用的各种结构和材料及其最终阻抗与湿电极的阻抗进行比较。最后，我们将最先进的电极和放大器与 IFCN 和 IEC80601-2-26 的标准进行比较。我们调查了瓶颈，并为未来关于无源和有源干电极以及 EEG 放大器的工作提出了指导方针。