基于复合多孔结构的离-电式柔性压力传感器

柔性电容式压力传感器能将外部力刺激转化为电容信号，且兼具良好的柔韧性，在人机交互界面、健康监测、电子皮肤等领域有着重要的应用。本研究围绕基于双电层（EDL）传感机理的离-电式压力传感器，以多孔复合离子材料为传感层，通过传感机理分析、有限元仿真和实验研究，深入探讨了多孔结构的孔隙率及压缩模量对传感器灵敏度的影响机制，为离-电式电容压力传感器的灵敏度提升提供新的策略，并为其在可穿戴、可涂覆以及透明传感等领域的应用提供了思路和证据。

本研究通过力学机理分析和有限元方法对多孔结构受压条件下的力学行为进行分析，发现多孔结构的压缩变形与离-电界面的协同作用是实现高传感性能的关键。有限元分析结果表明，高孔隙、低模量的孔结构能有效改善材料的压缩变形性能，提高受力过程中离-电界面接触面积的变化量，进而提升传感器的灵敏度。基于此思路，采用孔隙率为95.4%和压缩模量为3.4 kPa的聚氨酯（PU）-离子液体（IL）复合泡沫作为离子传感层，器件的灵敏度高达9 280 kPa-1，是目前已报道的离-电式压力传感器中的最高记录。同时该器件的响应速度快至10 ms，80 kPa压力下分辨率为0.125%，能在数千次的压缩或弯曲循环测试中保持力学稳定，在水波、水下振动和机器故障监测等领域展现出潜在的应用价值。

在复合多孔离子结构设计理念的基础上，直接采用IL活化的多孔布料作为离子传感层，研制出一种可穿戴式的压力传感织物。这种IL活化的方式可在服装的指定目标区域进行处理，工艺简单高效，制备的传感织物能感应到微弱的脉搏压力信号且兼具织物的柔性和舒适性。此外，依据超细银纳米线（AgNW）容易失稳弯曲的力学性质，得到具有良好力学稳定性的多孔电极层，结合醋酸纤维素（CA）-IL复合多孔膜，设计出一种通孔结构的多功能传感织物。该传感器的灵敏度达到4.46 kPa-1，响应时间为39 ms，能够清晰地采集多种人体运动和生理活动中的力学信息，且兼具防水、透气及抗菌等特点，在智能健康或运动监测中具有广阔的应用前景。

此外，本文以聚酰亚胺（PI）为基础材料，同样采用多孔复合离子层的设计策略，开发出像漆料一样可涂覆的耐高温压力传感涂料。与传统封装式器件相比，该传感涂料与基底结构的共形性更强，可涂覆在多种曲面的表面。等离子处理后，涂料的下电极与不锈钢基底间的粘接强度显著提升，其界面韧性高达413 J/m2。同时，涂料中的电极层与传感层间的界面韧性大于127 J/m2，无需使用额外粘结剂进行封装，表现出自粘附性。这种传感涂料在300 °C高温和2.5 MPa高压下仍能响应到外部力刺激，有望为离-电式柔性压力传感器的集成开辟一条新途径，并在紧固件应力松弛监测中显示出潜在的应用前景。

多孔结构带来的光散射使器件无法同时兼顾高灵敏和高透明。为解决这个难题，本研究提出在多孔结构中填充与其折射率相匹配的IL的方法，从而有效地保持其界面的连续性，降低光散射，致使复合离子膜的透明度高达94.8%。此外，该透明离子膜的表面保留有少量的凸起结构且韧性也显著提升，同时满足高透明、高韧性及高灵敏离-电式柔性压力传感器的设计需求。最终器件的透光度达到90.4%，灵敏度为1.194 kPa-1，能检测到低至0.4 Pa的微弱力信号，且具有较高的力学稳定性，在透明拨号手环、透明智能窗户中表现出较好的应用潜力。

本文分析了离-电式电容压力传感器传感的力学原理，提出了以复合多孔离子膜为基础的传感器设计思路，制备得到了超高灵敏、可穿戴式、可涂覆以及高透明的传感器件，为柔性电容式压力传感器的制备及应用提供了系列新的设计方案。

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