sensors Article Figure of Merit Enhancement of a Surface Plasmon Resonance Sensor Using a Low-Refractive-Index Porous Silica Film Qing-Qing Meng 1, Xin Zhao 1, Cheng-You Lin 1,*, Shu-Jing Chen 2, Ying-Chun Ding 1 and Zhao-Yang Chen 1,* 1 College of Science, Beijing University of ...