Fabrication and Functionalization of Distributed and Stretchable Sensor Networks for Structural Health Monitoring

Structural health monitoring (SHM) technology takes advantage of distributed sensors to detect the damage and assess the state of a structure. Owing to the development of modern CMOS and MEMS technology, millions of miniaturized sensors can be microfabricated at an unprecedented speed and scale. However, a standard process for manufacturing multimodal sensors in a platform and then integrating them into a large-sized structural component still requires further development. In this article, we describe process improvements to produce stretchable sensor networks with higher signal-to-noise ratios and higher measurement accuracy using conventional microfabrication techniques. Specifically, two improvements were accomplished: (1) aluminum was used to replace gold for significant cost and resistance reduction; (2) a shielding layer was added to mitigate the effects of electro-magnetic interference. The resulting stretched sensor network has 17 distributed and functionalized sensing nodes with low tolerance and high resolution. In addition, the network was handled with an in-house developed stretch machine to automatically expand it to cover a desired area. The released and stretched network is laminated into a flexible frame with edge-mount electronics for signal conditioning, processing, power and wireless communication capabilities. To demonstrate the business impact of the sensor network, a small composite wing will be created and the sensor network will be integrated into the wing for measurements of impact, strain and temperature. Collectively, the measurement results represent a robust and reliable sensing system that is able to generate superior state sensing and awareness capabilities for SHM-based applications.