PVA/BaTiO3复合薄膜的挠曲电响应及感知特性研究

Flexoelectric Response and Sensing Properties of PVA/BaTiO? Composite Films

摘要:

为提升传统压电器件对以弯曲应变为主的复杂形变响应效果，以聚乙烯醇（PVA）和BaTiO3为原料制备复合凝胶，引入壳聚糖（CS）和1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐离子液体[EMIM][TFSI]作为功能性组分参与材料构筑与响应调控，制备PVA/BaTiO3复合薄膜和传感器，采用SEM、EDS、XRD和FTIR对PVA/BaTiO3复合薄膜进行表征，通过自行搭建的挠曲电响应测试平台，基于挠曲电响应实验，考察PVA/BaTiO3复合薄膜传感器在弯曲形变电响应中的性能，分析了薄膜在不同弯曲角度下的响应行为，探讨了弯曲应变下的电荷转移机制。结果表明，PVA/BaTiO3复合薄膜传感器对30°以内的弯曲形变响应显著，响应电压与弯曲角度呈近似线性关系，最大响应电压可达3.96 V，挠曲电系数高达3.82 nC/m。PVA/BaTiO3复合薄膜传感器显示出良好的稳定性和耐用性，在3000 s的长时间使用后，电压衰减仅为3.7%；并具有温度（10～40 ℃）适应性强，输出电压基本保持稳定，变化量仅为2%。PVA/BaTiO3复合薄膜传感器在人体运动监测应用中，能够精确反映指关节（11°～25°）和膝关节（5°～16°）的弯曲角度，可有效感知人体指关节和膝关节的弯曲情况，响应电信号强度能够准确反映弯曲角度的变化。

Abstract:

To enhance the response performance of traditional piezoelectric devices to complex deformations dominated by bending strain, a composite gel was developed using polyvinyl alcohol (PVA) and barium titanate (BaTiO3) as base materials. Chitosan (CS) and the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]) were introduced as functional components to facilitate material structuring and response modulation. PVA/BaTiO3 composite films and corresponding sensors were fabricated, and their microstructure and composition were characterized via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The electromechanical response behavior of the composite films was investigated using a self-designed flexoelectric response testing platform. Bending-induced electrical outputs under varying bending angles were systematically analyzed to explore the charge transfer mechanism under mechanical deformation. The results demonstrate that the PVA/BaTiO3 composite film sensor exhibits a pronounced response to bending deformations within 30°, with the output voltage showing an approximately linear relationship with the bending angle. The maximum response voltage reaches 3.96 V, and the flexoelectric coefficient is as high as 3.82 nC/m. The sensor also shows excellent stability and durability, with only a 3.7% voltage attenuation after continuous operation for 3000 seconds. Moreover, the device maintains stable performance across a temperature range of 10~40 ℃, with voltage variation limited to within 2%. In practical applications, the PVA/BaTiO3 composite film sensor accurately detects joint bending, effectively reflecting finger joint (11~25°) and knee joint (5~16°) movements. The generated electrical signals reliably correspond to the degree of joint deformation, demonstrating the sensor"s strong potential for wearable human motion monitoring.