离-电型柔性触觉传感器的软材料分级微结构构筑及应用研究

  柔性触觉传感器是一类将外界机械刺激转化为电信号的柔性器件。通过材料和结构的设计，可赋予触觉传感器良好的柔性，实现在可穿戴设备、电子皮肤及智能机器人等领域的重要应用。同时，日益多样化的应用场景要求柔性触觉传感器具有高灵敏度、宽检测范围、可线性传感能力以及更多元的传感模式。离-电型柔性触觉传感器因结构简单、信噪比高、功耗低、抗干扰能力强等优点得到广泛研究。

  引入微结构如金字塔、微锥、半球等是提升柔性触觉传感器灵敏度的通用方法。但由于制备柔性触觉传感器的软材料是不可压缩的—即压缩过程中保持体积不变，受压时发生结构硬化并表现出对外界压力高抵抗性，使传感器的灵敏度随着压力的增加而显著下降、响应呈现显著的非线性。针对这一问题，本研究从材料的结构出发，通过界面结构的设计来解决软材料受压产生结构硬化的本征性问题。设计并制作一类分级微结构，有效提高结构的可压缩性和变形性，实现了柔性触觉传感器的灵敏度、传感范围、响应线性度及微结构检测能力等方面的性能提升。主要研究内容和结果如下：

  提出一种分级自填充结构，可有效提高传感界面的可压缩性，解决了柔性触觉传感器中软材料的结构硬化这一问题，结合离-电型传感机制，实现柔性触觉传感器的宽量程（0.08 Pa – 360 kPa）和高灵敏度（~ 3300 kPa^-1）的统一；同时，将高压区灵敏度提升四个数量级，并获得超高的高压压力分辨率（0.0056%）。分级自填充型传感器在航空压力测试、机器人触觉等领域具有潜在的应用前景。

  在实现传感器高灵敏度、宽量程的基础上进一步设计一种分级互锁结构，解决了由结构硬化问题导致触觉传感器呈非线性响应的问题，有效拓宽传感器的线性传感范围。在理论方面，系统阐述了器件线性传感机制，并定义S_P = S·ΔP为线性传感因子，用以评价触觉器件的线性传感能力，拓展触觉器件的性能评价指标。在性能方面，分级互锁结构的引入使界面接触面积随着压力线性增长，实现触觉器件的高灵敏度（~ 49 kPa^-1）、高线性度、宽线性传感范围（4 – 485 kPa）。在应用方面，将具有分级互锁微结构的柔性触觉传感器集成在机械手上，结合机器学习，实现机械手对物体的重量的识别，提升机器人触觉感知能力。

   在高灵敏度及宽线性传感范围的基础之上，进一步发展具有结构识别能力的触觉器件研究。通过对皮肤触觉的研究，提出压觉-滑动觉的双模态触觉感知模式。将仿生指纹结构与微结构化的离-电界面结合，实现双模态触觉器件高灵敏（~ 500 kPa^-1）、宽传感范围（~ 350 kPa）以及极短的响应/弛豫时间（~ 3 ms）等优异的压力传感性能，以及低结构检测限（l_min  = 15 μm，h_min = 6 μm）、高耐摩擦性等良好的滑动觉方面的性能。系统阐述了双模态器件的纹理（结构）识别机制，为触觉器件在外物识别方面的发展提供理论支持。在应用方面，将双双模态触觉传感器集成在机械手表面进行精细结构识别，帮助机器人识别20种织物，其准确率高达95%及以上，实现高于人的识别准确度。

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