Self-powered thin-film impedance spectroscopy sensor system to measure corrosion presence in aerogenerators or aircrafts

The Structural Health Monitoring (SHM) is a key technology to detect and prevent critical damages in different kind of structures. Corrosion is one of the main issues affecting metallic structures exposed to wet environments or affected by high levels of moisture, such as in offshore aerogenerators or aircrafts, and, therefore, is a critical parameter to be monitored. In this work, an on-line SHM sensor is presented, based on impedance spectroscopy techniques, which can be used to continuously measure corrosion in the surface of different kind of structures, and which could be implemented in airframe and wind energy generation structures. The impedance of an interdigitated sensor is measured in a frequency range between 16mHz and 200kHz, with resulting impedance values up to 100GOhm. The impedance sensor aims at being a completely wireless and autonomous solution: the sensor integrates wireless data communication and is self-powered by two independent energy harvesting systems. An RF antenna is used to harvest energy from a RF emitter in static and low range applications, while a flexible PV panel is installed to directly harvest energy from the environment, also in moving applications such as wind generator blades. Moreover, the use of thin-film and flexible electronics facilitates the integration of the sensor into any surface with very little aerodynamic impact. All the interdigitated sensor, the associated control electronics and the energy harvesting system can be implemented in polymeric thin flexible substrates, combining printed and hybrid electronics and allowing curved and complex geometries for the sensor device.