Advanced Composites and Hybrid Materials ( IF 23.2 ) Pub Date : 2022-01-22 , DOI: 10.1007/s42114-021-00396-w Xiaotong Liu 1 , Zijian Wu 1, 2 , Ye Wang 1 , Ling Weng 1, 2 , Ning Guo 2 , Dawei Jiang 3 , Tao Ding 4
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Ion conducting hydrogels are attracting increasing attention in wearable sensors, owing to their advantages of withstanding a large range of strains, good biocompatibility, and excellent sensing properties. However, simultaneous realization of the above advantages and other practical application requirements such as extreme environmental tolerance and optical transparency remains challenging. Herein, high-performance PVA/glycerol/sodium alginate(SA)/CaCl2 (PGSC) ionic hydrogel sensors with dual physically cross-linked network was fabricated to overcome these challenges. As the first cross-linked network, glycerol cross-linked PVA maintain the basic framework structure of the hydrogel. The second network was formed though ionic cross-linking between sodium alginate (SA) and multivalent cations (Ca2+). This ionic interaction can be regarded as sacrificial bonds to dissipate mechanical energy. Significantly, Ca2+ was introduced to the hydrogel by the water-glycerol mixed solvent displacement approach, not single solvent displacement approach reported by most literatures. Benefiting from the dual network structure, the hydrogel exhibited good mechanical properties (maximum strain 816%, maximum stress 2.29 MPa) as well as fast self-recovery ability after stretching. The introduction of a large number of ions imparted the hydrogel with high conductivity (2.08 × 10−2 S/cm), and high sensitivity over a relatively wide range (GF = 2.68 at 500% strain). The PGSC sensors exhibited good transparency (96.5% at 600 nm) and the ability to be used at extreme environments for a long time. Conductive hydrogels can also serve as monitoring devices to make accurate and stable electrical signal outputs to physiological signals emanating from various parts of the human body. The combination of these excellent capabilities highlights the great potential of PGSC hydrogel in wearable sensors and other flexible electronic device.
Graphical abstract
中文翻译：
通过互穿 Ca2+-SA 和甘油-PVA 双物理交联网络构建的高度可拉伸、传感耐用、透明且环境稳定的离子导电水凝胶应变传感器
离子传导水凝胶在可穿戴传感器中引起了越来越多的关注，因为它们具有承受大范围的应变、良好的生物相容性和优异的传感性能等优点。然而，同时实现上述优势和其他实际应用要求，如极端环境耐受性和光学透明度仍然具有挑战性。为了克服这些挑战，本文制备了具有双物理交联网络的高性能 PVA/甘油/海藻酸钠 (SA)/CaCl 2 (PGSC) 离子水凝胶传感器。作为第一个交联网络，甘油交联PVA保持了水凝胶的基本框架结构。第二个网络是通过海藻酸钠（SA）和多价阳离子（Ca2+ )。这种离子相互作用可以被视为耗散机械能的牺牲键。值得注意的是，Ca 2+通过水-甘油混合溶剂置换方法引入水凝胶，而不是大多数文献报道的单一溶剂置换方法。得益于双重网络结构，水凝胶表现出良好的力学性能（最大应变816%，最大应力2.29 MPa）以及拉伸后的快速自恢复能力。大量离子的引入赋予水凝胶高电导率（2.08 × 10 -2S/cm），并且在相对较宽的范围内具有高灵敏度（500% 应变时 GF = 2.68）。PGSC 传感器表现出良好的透明度（600 nm 时为 96.5%），并且能够在极端环境下长时间使用。导电水凝胶还可以作为监测设备，对人体各个部位发出的生理信号进行准确稳定的电信号输出。这些优异性能的结合凸显了 PGSC 水凝胶在可穿戴传感器和其他柔性电子设备中的巨大潜力。
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