Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK.
Soft Matter. 2019 Oct 28;15(40):8001-8011. doi: 10.1039/c9sm01046g. Epub 2019 Aug 30.
New materials and technologies in sensing and actuation have led to the development of soft actuators and robots for biomedical systems, assistive devices, exploration and rescue. The use of integrated actuation-sensing materials in such systems is gaining interest, but there are few examples where the body of the actuator or soft robot acts as the sensing element. The development of smart soft actuators that have inherent sensing capabilities can provide advantages of high sensitivity, ease of manufacture and cost efficiency, without impairing actuator dynamics. To achieve this goal, we have prepared soft actuators using piezoresistive composites based on a silicone matrix impregnated with short conductive carbon fibres. The optimum carbon fibre volume fraction to achieve a frequency independent conductivity and piezoresistive response was determined, with in situ mechanical and electrical testing to quantify the piezoresistive properties. The frequency dependent electrical properties and sensitivity of the composites with deformation was explained on the basis of a microstructural resistor-capacitor network model. The piezoresistive composites were used to successfully manufacture a pneumatic soft finger actuator where the resistance change of the actuator body was able to monitor deformation with applied pressure. The creation of soft actuators with an inherent sensing capability is a promising approach for control and operation of future soft robots.
新型传感和致动材料推动了用于生物医学系统、辅助设备、探索和救援的软致动器和机器人的发展。在这些系统中使用集成的致动-传感材料越来越受到关注，但很少有例子将致动器或软机器人的主体用作传感元件。开发具有固有传感能力的智能软致动器可以提供高灵敏度、易于制造和成本效益的优势，而不会影响致动器的动力学。为了实现这一目标，我们使用基于硅树脂基体的压阻复合材料制备了软致动器，该基体中浸渍了短导电碳纤维。确定了实现频率无关电导率和压阻响应的最佳碳纤维体积分数，并通过原位机械和电气测试来量化压阻性能。基于微结构电阻-电容网络模型解释了复合材料的频率相关电特性和变形时的灵敏度。压阻复合材料成功地制造了气动软指致动器，其中致动器主体的电阻变化能够监测施加压力时的变形。具有固有传感能力的软致动器的创建为未来软机器人的控制和操作提供了一种很有前途的方法。
