Abstract: With the growing attention to healthy living, flexible wearable sensors have found widespread applications in health monitoring, motion tracking, human-computer interaction, and other fields. Compared to traditional rigid sensors, flexible sensors demonstrate superior flexibility, stretchability, and adaptability, enabling them to closely adhere to the human body or be integrated into clothing for real-time monitoring of biological signals and environmental changes. Especially in the monitoring of minute deformations, flexible sensors exhibit significant advantages, maintaining stable operation under complex dynamic conditions. However, existing flexible sensors still face numerous challenges in terms of sensitivity, stability, and responsiveness. Therefore, the research on high-performance sensor materials with excellent mechanical properties and electrical conductivity has become the focus of current research.
In this paper, nano-sized copper oxide (CuO) was synthesized using the sol-gel method and compounded with polyvinyl alcohol (PVA) to prepare CuO/PVA conductive hydrogels (abbreviated as CP) with sensing capabilities through a freeze-thaw cycling process. This method features straightforward operations and does not require sophisticated equipment, as the material formation can be achieved simply by controlling the freeze-thaw cycles, thereby reducing preparation costs and technical barriers. Furthermore, through systematic research on the doping ratio of CuO and other process conditions, it was determined that the comprehensive performance of the CP conductive hydrogels reaches its optimum when the mass fraction of copper oxide is 0.6% (abbreviated as CP0.6). Finally, a polyester/copper oxide/polyvinyl alcohol (PET/CuO/PVA, abbreviated as PCP) yarn sensor with excellent sensing performance was prepared using the dip-coating method.
The research results show that the CP0.6 conductive hydrogel exhibits excellent electrical and mechanical properties. When the mass fraction of nano-CuO is 0.6%, its conductivity reaches a maximum value of 0.16 S/m, with a response sensitivity factor of 2.78, and it demonstrates rapid dynamic response within the tensile strain range. Moreover, the material's stability and reliability under dynamic conditions make it have certain application potential in the fields of wearable devices and flexible sensors. On the other hand, the conductivity of the PCP15 yarn sensor can reach up to 0.89 S/m, exhibiting fast response capability and good strain sensitivity, particularly showing segmented linear sensitivity characteristics within the small strain range (1%–5%). Furthermore, the PCP15 yarn sensor can effectively monitor subtle vibrations and the bending of joints such as the fingers, wrists, and elbows, and it can operate stably and adapt to motion monitoring of different amplitudes. This makes the PCP15 yarn sensor have application potential in motion tracking and smart wearable devices. In the future, the optimization of its conductive network structure and the bonding performance of the fiber interface is expected to further enhance its application potential and commercial value.

Key words: conductive hydrogel, yarn sensor, sensing performance, flexible wearable sensor

摘要： 为了制备能够监测微小形变的纱线传感器，以聚乙烯醇(PVA)为原料，采用溶胶-凝胶法合成纳米氧化铜(CuO)，并将其与PVA复合，制得CuO/PVA导电水凝胶，再通过浸渍提拉法制备了涤纶/聚乙烯醇/纳米氧化铜(PET/CuO/PVA)纱线传感器。经过测试与分析，结果表明：当CuO质量分数为0.6%时，CuO/PVA导电水凝胶的电导率为0.16 S/m，且其拉伸应变性能良好、稳定性较高。当PET/CuO/PVA纱线传感器中CuO的质量分数为15%时，纱线传感器的电导率可达到0.89 S/m，响应速度小于71 ms；在1%~5%的应变范围内，其灵敏度达到了2.38，并且能够实现连接蓝牙实时输出。研究表明所制备的PET/CuO/PVA纱线传感器在柔性可穿戴传感器领域具有潜在的应用价值。

关键词: 导电水凝胶, 纱线传感器, 传感性能, 柔性可穿戴传感器