Development of low-cost fiber optic temperature sensing interrogators for Li-ion battery thermal monitoring

The cost of conventional fiber optic interrogation system has been the limiting factor for its commercialization and market penetration into electrical asset monitoring where the room for capital investment on sensors is relatively small. The ability to deliver portable and cost-effective sensors without compromising their performances becomes critical. Here, we demonstrate the application and low-cost interrogation strategy for intensity-modulated evanescent wave fiber temperature sensor made of plasmonenabled thin films. Optical transmittance change resulting from the thermal damping of plasmonic absorption intensity is converted into analog voltage signals, then transmitted wirelessly through a set of commercial wireless hardware to enable remote monitoring capability. The temperature response is compared against a custom-designed intensity-based Fiber Bragg Grating (FBG) interrogator with Long Period Grating (LPG) edge filter, where its temperature and strain sensing performance of the intensity-based FBG interrogator is presented and discussed. Both sensors are deployed to monitor the dynamic thermal behavior of Li-ion polymer pouch cell under normal charging/discharging conditions. Finally, the initial design and implementation of an energy harvesting circuit that powers the low-cost wireless interrogator from a potential instrumented power conversion/storage device itself is also discussed.