离子皮肤，是一种基于离子导体制备得到的电子皮肤。它与传统电子皮肤的区别在于离子皮肤是以离子来传输信号，而后者则是利用电子来传递信号。近年来，离子皮肤在人机交互、健康监测以及神经系统的研究等方面应用愈加广泛；同时，与其相关的研究也契合了我们国家在十四五规划中对人工智能、集成电路、脑科学与类脑研究、临床医学与健康等领域攻关的需求。无论是在人工智能、脑科学还是在医疗健康领域，电生理信号都是十分重要的研究和参考对象。表皮电生理信号监测是可穿戴医疗保健的重要组成部分，但其中一大挑战是表皮电生理信号的微弱强度；此外，表皮电生理信号的检测环境也较为复杂。高导电性的电极可以灵敏检测出微弱的信号，而稳定的电极材料则能够适应复杂的检测环境。然而在电极材料的选择上仍存在着两个问题：1. 基于水凝胶的离子导体有着较高的电导率，但存在潮湿环境下溶胀和干燥环境下脱水的问题，缺乏稳定性；2. 基于非水体系离子凝胶的离子导体能实现较好的水下稳定性，但是其电导率普遍位于10^-6-10^-4 S cm^-1之间，远未达到电生理检测所需的高电导率（~10^-3 S cm^-1）。

本论文所述工作以上述问题作为切入点，设计了一种水下稳定、高导电性，兼具光学伪装的离子皮肤，为在水环境下进行表皮电生理信号长期监测提供了可能。本论文的研究内容包括以下几个部分：

一、兼具水下稳定性和高电导率的离子导体的制备与表征。首先使用逐步聚合的方法，将含氟链段引入聚氨酯，再将含氟聚氨酯与离子液体共溶液混合，制备得到。之后对该离子导体进行了表征，验证了其中存在的氟—阳离子相互作用，并探究了相互作用对离子电导率、机械性能和水下稳定性的影响，测试了材料的透明度。得益于氟—阳离子相互作用，该离子皮肤获得了显著的高离子电导率（1.04 × 10^-3 S cm^-1）、高透光率（92%）和机械强度（杨氏模量3.1 MPa）。通过富氟链段对阳离子的约束，其离子电导率即使在剧烈洗涤后也能保持稳定。

二、水下稳定离子皮肤电生理电极的制备与电生理检测应用。基于高电导率水下稳定离子导体，制备了可以在大气和水环境中准确测量各种电生理信号的离子皮肤电极，表现出强大而出色的信号质量。通过对心电信号和表面肌电信号的检测与分析，直观地将离子皮肤电极与商用Ag/AgCl电极的性能从T/R比、信噪比和归一化基线噪声几个方面进行了比较；同时采用普通聚氨酯制备的离子皮肤电极作为对照，验证了本工作中离子皮肤的水下稳定性和耐用性。

三、智能腕带的设计与长期穿戴测试。采用水下稳定离子皮肤电极作为测量电极，设计制备出了可反复清洗并长期佩戴的智能腕带。由于该离子皮肤具有高电导率和水下稳定的性质，该智能腕带在反复清洗和长达一周的佩戴过程中能够对心电信号进行持续稳定的监测。

Ionic skin, based on ionic conductor, is a category under the electronic skin. Different from traditional electronic skin, ionic skin transduces signals using ions, while the other one using electrons. In recent years, ionic skin is generally widespread in the application for human-machine interfaces, health caring, and studied of nerve system. Meanwhile, the related research on ionic skin also fits the needs of our country to tackle key problems in frontier fields in the 14th Five-Year Plan, such as artificial intelligence, integrate circuit, encephalon science as well as brain-like rearch, and clinical medicine with health. Wherever in the field of artificial intelligence, encephalon science or clinical healthcare, electrophysiological signals are always playing an important role. The monitoring of surface electrophysiological signals is an essential part of wearable healthcare. But here faces a challenge that the intensity of surface electrophysiological signals is too weak. In addition, monitoring atmosphere of surface electrophysiological signals is also complex. Highly conductive electrode could sensitively detect week signals; and the stability of materials enables electrodes adapt to complicated environment. However, there are two problems still in the selection of electrode materials: 1. Ionic conductors based on hydrogels are highly conductive but easily swollen in humid circumstance or dehydrated in dry air, lacking of stability. 2. Ionogels based on non-aqueous system could be underwater stable, but its conductivity locates within 10^-6-10^-4 S cm^-1, which is so far from the need of electrophysiological monitoring (~10^-3 S cm^-1).

In this thesis, a highly conductive and optical camouflaged ionic skin is designed and fabricated, aiming to solve the above problems. This kind of ionic skin gives an access to long-term monitoring of surface electrophysiological signals. The performed preparation and application include the following sections:

1. Fabrication and characterizations of underwater stable and highly conductive ionic conductor. At first, polyurethane was step-polymerized with fluorine-contained segments. Then the polymer was mixed with ionic liquid in same solvent. Characterization of this ionic conductor has proved the existence of fluorine-cation interaction. Its influence on ionic conductivity, mechanic properties, transparency and underwater stability was tested. Due to fluorine-cation interaction, our ionic skin gains high conductivity (1.04 × 10^-3 S cm^-1), super transmittance (92%) and mechanical strength (Young’s modulus 3.1 MPa). Through the confinement of cations by fluorine-rich segments, its ionic conductivity remains stable even after rinsing in water or vigorous washing.

2. Fabrication and electrophysiological signal monitoring of underwater stable ionic skin electrode. Based on highly conductive underwater stable ionic conductor, we have prepared ionic skin electrodes that could accurately measure various electrophysiological signals in atmospheric and aqueous environments, exhibiting robust and excellent signal quality. Through the detection and analysis of ECG and surface EMG signals, we compared the performance of ionic skin electrodes with commercial Ag/AgCl electrodes in terms of T/R ratio, signal-to-noise ratio and normalized baseline noise. The ionic skin electrode prepared from polyurethane was used as a control to verify the underwater stability and durability of the ionic skin in this work.

3. Design and long-term wear test of smart wristband. Using the underwater stable ionic skin electrode as the measurement electrode, a smart wristband that could be repeatedly washed and worn for a long time is designed and fabricated. Due to the high conductivity and underwater stability of our ionic skin, the smart wristband enables continuous and stable monitoring of ECG signals, during the repeated washing and a one-week wearing.