Conductive hydrogels are widely used in electronic skin, wearable sensing devices, human–machine interfaces, and soft robots because of their high elasticity, biocompatibility, and conformability in interfacial contact. However, hydrogels lose electrical conductivity and flexibility due to water crystallization at low temperatures, which severely limits their applications in the frigid regions. In this study, we propose to design a metal–ligand ionic hydrogel (PAASP-Zr-LiCl) through the formation of a stable coordination bond between the dicarboxylic acid group monomer poly(N-acryloyl aspartic acid) (PAASP) and zirconium ion (Zr4+). Zr4+–COO- metal-coordination complex as physical cross-linking points of the network can effectively improve the mechanical properties of hydrogels. By introducing lithium chloride (LiCl), the hydrogel obtained excellent anti-freezing properties (crystallization temperature < -80 °C) and high ionic conductivity (8.45 S/m). The LiCl molecules enhance the interaction between the polymer network and water molecules. The ionic hydrogel-based strain sensors exhibited a high gauge factor of 3.21. Combining hydrogel sensors with soft grippers can realize continuous and stable monitoring of grasping objects at low temperature of −30 °C. By integration of excellent flexibility (elongation at break 837.4 %), good ionic conductivity, high sensitivity, and excellent anti-freezing properties, the anti-freezing ionic hydrogel has a wide range of applications in the frigid regions of the plateau.

中文翻译：

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使用 Zr4+-二羧酸配位配合物增韧抗冻离子水凝胶，用于低温传感应用


导电水凝胶因其高弹性、生物相容性和界面接触的顺应性而广泛用于电子皮肤、可穿戴传感设备、人机界面和软机器人。然而，由于水在低温下结晶，水凝胶失去了导电性和柔韧性，这严重限制了它们在寒冷地区的应用。在这项研究中，我们建议通过在二羧酸基团单体聚（N-丙烯酰天冬氨酸）（PAASP）和锆离子（Zr4+）之间形成稳定的配位键来设计金属-配体离子水凝胶 （PAASP-Zr-LiCl）。Zr4+–COO-金属配位配合物作为网络的物理交联点，可以有效改善水凝胶的力学性能。通过引入氯化锂 （LiCl），水凝胶获得了优异的抗冻性能（结晶温度 < -80 °C）和高离子电导率 （8.45 S/m）。LiCl 分子增强了聚合物网络和水分子之间的相互作用。基于离子水凝胶的应变传感器表现出 3.21 的高应变系数。将水凝胶传感器与软夹持器相结合，可以在 -30 °C 的低温下实现对抓取物体的连续稳定监测。 通过整合出色的柔韧性（断裂伸长率 837.4%）、良好的离子导电性、高灵敏度和出色的防冻性能，防冻离子水凝胶在高原的寒冷地区具有广泛的应用。