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

这个小型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并嵌入到复合材料中。一期工程表明，聚偏氟乙烯(PVDF)薄膜完全可以作为一种新型传感器材料。还确定了该传感器非常容易制造，并且即使在非常高的应变下，传感器的输出也具有高度的重复性和线性。第一阶段的研究还发现，PVDF薄膜的两个与温度相关的效应，即热释电效应和压电系数与温度的关系，可以得到修正。根据这些结果，可以得出结论：该材料是应变敏感的，可以用于制造应变传感器件。在第二阶段，数据遥测和数据采集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，利用该原型系统可以设计和制造许多专门的传感器，如加速度计、位移计、疲劳寿命计数器等，用于商业应用。研究的任务包括：(1)传感器设计，研究用于保护的传感元件封装、最终应用的传感器尺寸、温度影响的消除、基于IC的车载信号放大、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用性，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，包括将硬件接口到商业可行的系统中，并开发存储和可视化软件，(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(23万座)的桥梁结构存在缺陷或已过时。全国每年在大桥修复上的花费约为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十分重要。该状态监测系统还可以作为地震等自然灾害事件应急响应的预警系统。因此，用于基础设施监测的无线PVDF应变传感器具有广阔的商业应用前景。最终用户包括各级政府、私营公司和行业、建筑物业主和基础设施管理人员以及地震和其他自然灾害的应急机构。

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.