【作者】 陈明；

【导师】 车录锋；

【作者基本信息】 浙江大学 ， 电子科学与技术， 2024， 硕士

【摘要】 随着柔性传感技术的快速发展,柔性应变传感器在可穿戴式电子设备、人机交互、软体机器人等领域得到广泛应用,同时,对柔性应变传感器的灵敏度、检测范围等主要性能的要求也在不断提升。近年来,受蜘蛛腿部狭缝器官启发的基于微裂纹结构的柔性应变传感器因其具有极高的灵敏度而受到广泛的关注。然而,受裂纹应变传感器本身的原理特点和导电金属层的结构特征等因素限制,裂纹应变传感器存在裂纹产生具有随机性以及检测范围较窄这两个问题,裂纹的随机产生会影响裂纹应变传感器的灵敏度和稳定性。为此,本文从结构创新和材料改进两方面入手,分别利用倒金字塔微结构的应力集中效应诱导产生规则线形微裂纹和对柔性基底进行导电化处理的方法,设计并制备出基于倒金字塔诱导微裂纹结构的柔性应变传感器,从而解决上述两个问题。为了增强裂纹的可控性并提高传感器的灵敏度,本文制备出一种以聚二甲基硅氧烷(Polydimethylsiloxane,PDMS)为柔性基底,以金属Ti/Au为导电金属层的基于倒金字塔诱导微裂纹结构的单导电层柔性应变传感器。该传感器表面分布有倒金字塔微孔阵列,当受到拉伸力产生应变时,可以在倒金字塔微孔附近形成应力集中,从而在相邻倒金字塔顶部尖端之间诱导形成与拉伸方向垂直的线形微裂纹。这种规则的线形微裂纹能够有效改变电流的传输通路,从而提高传感器的灵敏度。测试表明,该单导电层柔性应变传感器在0～7.6%和7.6%～10%的应变范围内分别具有761和9327的灵敏度,响应时间和恢复时间分别为77 ms和82 ms。此外,该传感器成功检测了人体关节运动和颈部弯曲的方向,表明其在手势识别、拉伸方向检测等方面具有良好的应用前景。为了使上述单导电层柔性应变传感器具有更宽的检测范围,本文对PDMS柔性基底掺杂多壁碳纳米管(Multi-Walled Carbon Nanotubes,MWCNTs)进行导电化处理,从而在较大的拉伸状态下为断裂的导电金属层提供电流通路。通过研究多壁碳纳米管/聚二甲基硅氧烷(MWCNTs/PDMS)导电复合材料的电学性质、拉敏性质、力学性质与MWCNTs的质量分数的关系,确定MWCNTs掺杂质量分数为5 wt%,并最终制备出以金属Ti/Au为导电金属层,以MWCNTs/PDMS导电复合材料为可伸展导电层的基于倒金字塔诱导微裂纹结构的双导电层柔性应变传感器。MWCNTs/PDMS导电复合材料具有良好的导电能力和拉敏性质,为传感器提供了更宽的检测范围及较大拉伸状态下良好的灵敏度。测试表明,改进后的双导电层柔性应变传感器不仅保留了与单导电层柔性应变传感器相似的性能:在7.7%～10.5%的应变范围内具有9446的灵敏度,响应时间和恢复时间分别为91 ms和80 ms,而且将最大检测范围从10%提高至22%,分别在10.5%～13.5%和13.5%～22%的较大拉伸状态下具有1653和175的灵敏度。更多还原

【Abstract】 With the rapid development of flexible sensing technology,flexible strain sensors have been widely used in wearable electronic devices,human-computer interaction,soft robotics,etc.At the same time,the requirements for the main performance such as the sensitivity and the sensing range of flexible strain sensors are also increasing.In recent years,flexible strain sensors with microcrack structures inspired by spider leg slit organs have gained widespread attention due to their high sensitivity.However,limited by the principles of the crack-based strain sensors and the structural characteristics of the conductive metal layer,the crack-based strain sensors have two problems:the randomness of the crack generation and the narrower sensing range,the random generation of the crack will affect the stability and the sensitivity of the crack-based strain sensors.Therefore,this paper starts with structural innovation and material optimization,using the stress concentration effect of inverted pyramid microstructures to induce regular linear microcracks to improve the sensitivity and conducting treatment on flexible substrates to improve the sensing range of the sensor.These approaches lead to the design and fabrication of a flexible strain sensor based on inverse pyramid-induced microcracks,effectively solving the above two problems.To enhance the controllability of the cracks and improve the sensitivity of the sensor,this paper prepares a single-conductive layer flexible strain sensor based on inverted pyramid-induced microcrack structures using polydimethylsiloxane(PDMS)as the flexible substrate and metal Ti/Au as the conductive metal layer.The sensor has an array of inverted pyramid holes distributed on the surface.When subjected to tensile stress,the stress concentration can be formed near the inverted pyramid holes,inducing the generation of linear microcracks perpendicular to the strain direction between the tips of adjacent inverted pyramids.Such regular linear microcracks can effectively change the current transmission path,thus improving the sensitivity of the sensor.The testing results show that the single-conductive layer flexible strain sensor has a sensitivity of 761 and 9327 in the strain range of 0～7.6%and7.6%～10%,respectively,a response and recovery times of 77 ms and 82 ms,respectively.In addition,the sensor has potential applications in health monitoring and human-computer interaction,such as human joint motion recognition and neck bending direction detection.To make the above single-conductive layer flexible strain sensor with high sensitivity have a wider sensing range,in this paper,the PDMS flexible is doped with multi-walled carbon nanotubes(MWCNTs)to undergo conductive treatment to provide current paths for the broken conductive metal layer in a high-stretching state.By investigating the relationship between the electrical properties,strain-electrical properties,mechanical properties of MWCNTs/PDMS conductive composite and the mass fraction of MWCNTs,the optimum doping mass fraction of MWCNTs was determined to be 5 wt%,and finally prepared a dual-conductive layer flexible strain sensor based on inverted pyramid-induced microcrack structures with metal Ti/Au as the conductive metal layer and MWCNTs/PDMS conductive composite as the stretchable conductive layer.The MWCNTs/PDMS have good conductivity and strain-electrical properties,which provide the sensor with a wider sensing range and good sensitivity in a high-stretching state.The testing results show that the optimized dual-conductive layer flexible strain sensor not only retains a similar performance with the single-conductive layer flexible strain sensor:a high sensitivity of 9446 in the strain range of 7.7%～10.5%,a short response and recovery time of 91 ms and 80 ms,respectively,but also improves the maximum sensing range from 10%to 22%with a high sensitivity of 1653 and 175 in the strain range of10.5%～13.5%and 13.5%～22%,respectively.更多还原