SBIR Phase II: A Wireless Polyvinylidene Flouride (PVDF) Strain Sensor for Infrastructure Monitoring

这个小企业创新研究第二阶段项目将制造一个PVDF应变传感器原型，它可以安装在结构上，也可以嵌入到复合材料中。一期工程表明，聚偏氟乙烯（PVDF）薄膜可以作为一种新型传感器材料。还确定该传感器非常容易制造，并且即使在非常高的应变下，传感器输出也是高度可重复和线性的。一期研究还发现，PVDF膜的热释电效应和压电系数温度依赖性这两个与温度相关的效应是可以修正的。结果表明，该材料具有应变敏感性，可用于制作应变传感器件。在第二阶段，数据遥测和数据采集和处理子系统将与传感器集成。无线PVDF传感器系统的原型将在实验室进行测试和评估，通过该系统，可以设计和制造许多专业传感器，如加速度计，位移计，疲劳寿命计数器等，用于商业应用。学习任务包括：(1)传感器设计，研究传感元件的保护封装、传感器的最终应用尺寸、温度效应的消除、基于IC的板载信号放大、频率响应特性和功率要求；(2)传感器在不同环境条件下的耐久性，如温度、湿度和循环疲劳载荷；(3)数据遥测系统，包括单通道和多通道无线数据传输，以及将传输范围扩大到一英里以上；(4)多通道数据采集和处理，包括将硬件连接到具有商业可行性的系统中，并开发用于存储和可视化的软件；(4)用于基础设施监测的无线PVDF传感器系统的现场测试、应用和评估。在美国现有的所有公路桥梁中，超过三分之一（23万）要么存在结构缺陷，要么已经过时。全国每年在桥梁修复上花费约50亿美元。监测基础设施对于准确确定其健康状况和估计其剩余寿命非常重要。状态监测系统还可作为地震等自然灾害事件应急响应的预警系统。因此，无线PVDF应变传感器在基础设施监测中的商业应用是广泛的。最终用户包括各级政府、私营公司和行业、建筑业主和基础设施管理机构，以及地震和其他自然灾害的应急响应机构。

This Small Business Innovation Research Phase II project will fabricate a prototype PVDF strain sensor, which can be mounted on structures and embedded into composites. The Phase I project demonstrated that a polyvinylidene flouride (PVDF) film satisfactorily qualifies as a new sensor material. It was also determined that the sensor is very easy to fabricate and that the sensor output is highly repeatable and linear even at very high strains. Phase I research also found that two temperature related effects of PVDF film, pyroelectric effect and piezoelectric coefficients temperature dependence, can be corrected. Based on these results it was concluded that the material is strain sensitive and can be utilized to produce the strain sensing devices. In Phase II, data telemetry and data acquisition and processing subsystems will be integrated with the sensor. The prototype of the wireless PVDF sensor system will be tested and evaluated in laboratory, by which numerous specialized sensors, such as accelerometer, displacement gauge, fatigue life counter, etc., can be designed and fabricated for commercial applications. The tasks of study include: (1) Sensor design to study sensing element encasement for protection, sensor dimension for end application, elimination of temperature effect, IC based onboard signal amplification, frequency response characterization, and power requirements, (2) Durability of sensor under different environment conditions, such as temperature, humidity, and cyclic fatigue loading, (3) Data telemetry system including single and multi-channel wireless data transfer as well as scaling up of transmission range to over a mile, (4) Multi-channel data acquisition and processing including interfacing hardware into a system that is commercially viable and developing the software for storage and visualization, and (4) Field tests, application and evaluation of the wireless PVDF sensor system for infrastructure monitoring. Over one third (230,000) of all highway bridges existing in US are either structurally deficient or obsolete. About $5 billion is spent annually on the bridge rehabilitation nationwide. Monitoring infrastructures is important in determining precisely their health conditions and estimating their remaining life. The condition monitoring system can also be used as a warning system in emergency response to earthquake and other nature disaster events. Therefore, the commercial application of the wireless PVDF strain sensors for infrastructure monitoring is broad. The end users include governments at all levels, private companies and industries, building owners and infrastructure manages, and emergency response agencies for earthquakes and other natural disasters.