RFID-inspired wireless microsensors for structural health monitoring

Organizations and assets employ structural health monitoring (SHM) techniques to collect data suitable for fault detection, non-destructive evaluation, system health tracking, and condition-based maintenance. The additional costs of these monitoring systems are justified based on improved efficiency, longer equipment lifetime, and enhanced safety levels. However, the installation and maintenance cost of a wired sensor node has limited the proliferation of these technologies. The evolution of inexpensive wireless communication, with installation costs being a fraction of a wired sensor point, as well as the elimination of manual checking and associated labor costs, has increased the application of SHM and process monitoring in a greater percentage of critical components, as well as additional medium- and low-importance equipment. However, there is currently a significant lack of wireless sensor technologies that can operate maintenance-free for extended periods of time in harsh environments and embedded deep within structures. Low-cost, low-profile, battery-less radio-frequency identification (RFID)-based wireless monitoring systems integrating MEMS devices with inductive coupling, RF backscatter, and wireless power transfer approaches, similar to those that have enabled the proliferation of RFID technology, have the potential to allow SHM within environments not conducive to electronics or batteries, such as in applications requiring operation at high or low temperature extremes, monitoring in caustic environments, operation in radiation environments, and permanent embedding within structures. This paper will present RFID-inspired wireless microsensors for corrosion monitoring, strain sensing, and impact detection utilizing MEMS-based sensors to achieve low-profile, small form factor, and robust devices. Corrosion monitoring devices utilize microfabricated arrays of electrical resistance probes, as well as nanolaminated mass-loss coupons. Strain and impact detection devices employ on micromachined piezoelectric materials. When coupled to RFID-inspired wireless approaches, the resulting sensor “tags” are small, thin, and inexpensive, while also realizable in material systems suitable for harsh environment operation.