Structural Health Diagnosis combined with IoT technology. Credit: Tomoki Uchiyama, Chao-Nan Xu et al.
Tohoku University researchers have developed a novel material to record stress history through luminescence. By applying the material to the surface of key infrastructures, researchers can observe changes in the luminescence to identify stress to key infrastructure.
The material, published in Applied Physics Letters, records stress with a Mechanoluminescent effect dubbed “afterglow”. Mechanoluminescent materials have been employed in the past to visualize stress after application to the surface of structures. But current materials can only be observed at the moment of stimulation and information about past stimuli cannot be retrieved.
The material developed by the researchers employs Pr-doped Li0.12Na0.88NbO3 (LNNO) which has mechanical recording functionality. To retrieve the historical data, the material is applied as a coating and later irradiated with a flashlight. The afterglow produced can then be analyzed using cameras or light sensors. During development, the team demonstrated not only the accuracy of the material but also its information retention capabilities, ultimately finding that stress information was available even after five months.
"What makes our material truly innovative is that it operates without a power supply, complex equipment, or on-site observation and is easily combined with IoT technology," said Chao-Nan Xu, Tohoku University professor. "Our findings are expected to alleviate the shortage of manpower in structural diagnosis, and lower costs,"