Alves-Lima DF, Schlegl H, Williams BM, Letizia R, Dawson R, Lin H. Observing liquid water build-up in proton exchange membrane fuel cells using terahertz imaging and high-resolution optical gauging. In2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) 2020 Nov 8 (pp. 1-2). IEEE.