Fully distributed in situ thermal characterization of PEM fuel cells using chirped fiber Bragg gratings

Accurate in-situ characterization of temperature gradients within the membrane electrode assembly (MEA) of proton

exchange membrane fuel cells (PEMFCs) remains a significant challenge. In this work, we present a fully distributed,

direct in-situ temperature sensing approach based on chirped fiber Bragg gratings (CFBGs). Exploiting the intrinsic

wavelength-to-position mapping of CFBGs, 3 cm-long gratings are embedded within key MEA layers to enable spatially

resolved thermal measurements. Short-time Fourier transform (STFT)–based spectroscopic demodulation is employed to

reconstruct transient heat transfer and local temperature distributions with sub-millimeter spatial resolution. The proposed

method exhibits a linear response over a temperature range of 30°C to 200°C, enabling continuous, high-resolution

monitoring of MEA thermal gradients. This approach provides a powerful tool for real-time thermal diagnostics and

performance optimization of PEMFC systems.