Ultrastable, stretchable, highly conductive and transparent hydrogels enabled by salt-percolation for high-performance temperature and strain sensing
Ultrastable, stretchable, highly conductive and transparent hydrogels enabled by salt-percolation for high-performance temperature and strain sensing
复制标题
通过盐渗滤实现超稳定、可拉伸、高导电性和透明的水凝胶，用于高性能温度和应变传感
DOI：
10.1039/d1tc02506f
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发表时间：
2021-07-05
影响因子：
6.4
通讯作者：
Wu, Jin
中科院分区：
文献类型：
--
作者：
Wu, Zixuan;Shi, Wenxiong;Wu, Jin
离子水凝胶是制造可拉伸电子产品的有希望的候选者，但在干燥和冷冻耐受性方面的不足严重限制了它们的应用。在这里，我们报告了一种简单而通用的盐渗透策略，以制造具有优异的冷冻和干燥耐受性，高导电性和抗膨胀能力的水凝胶，用于在广泛的温度范围内进行敏感温度和应变检测。我们发现溴化锂（LiBr）是各种盐中最有效的水凝胶干燥和冷冻抑制剂。50%溴化锂渗透的水凝胶即使在-78.5℃或环境空气中也能保持超高的拉伸性（625%的应变）和导电性一年。通过密度泛函理论（DFT）在分子尺度上的模拟，了解了LiBr在抑制水凝胶干燥和冻结中的重要作用，揭示了Li+-H2O和Br—H2O稳定簇的形成。结果表明，LiBr的引入提高了材料的温度和应变传感性能，如稳定性和工作温度范围。多功能透明传感器具有高热敏度（2.54%/℃）、宽温度检测范围（-78.5 ~ 97℃）、低检出限（0.1%应变）、低滞后和基线漂移等特点。由于水凝胶对大范围温度的高耐受性，即使在-20℃下也能保持应变传感能力。利用基于水凝胶的表皮传感器，可以实时监测面部表情、单词发音和膝盖弯曲等各种生理信号。
Ionic hydrogels are promising candidates for fabricating stretchable electronics, but the deficiency in drying and freezing tolerances severely limits their application. Here, we report a facile and versatile salt-percolated strategy to fabricate hydrogels with exceptional freezing and drying tolerances, high conductivity, and anti-swelling ability for sensitive temperature and strain detection within a broad temperature range. We discovered that lithium bromide (LiBr) was the most effective drying and freezing inhibitor for hydrogels among the various salts. The 50 wt% LiBr-percolated hydrogels retained ultrahigh stretchability (625% strain) and conductivity even at -78.5 degrees C or in ambient air for a year. The important role of LiBr in inhibiting the drying and freezing of hydrogels was understood using density functional theory (DFT) simulations on a molecular scale, revealing the formation of stable Li+-H2O and Br--H2O clusters. It was found that the introduction of LiBr enhanced the temperature and strain sensing performance, e.g., the stability and working temperature range. Multifunctional transparent sensors exhibited a high thermal sensitivity (2.54%/degrees C), broad temperature detection range (-78.5 to 97 degrees C), low detection limit (0.1% strain), and low hysteresis and baseline drift in cycling strain sensing. Attributed to the high tolerance of hydrogels to a wide range of temperatures, the strain sensing ability was maintained even at -20 degrees C. Various physiological signals, such as facial expressions, word pronunciation and knee bending, are real-time monitored using hydrogel-based epidermal sensors.