In some embodiments, a lateral circulate strip could also be moist with a fluid with an index of refraction larger than water, such as an index of refraction of 1.40, 1.45, 1.50, or 1.55. An index near that of the substrate or membrane (1.50 for nitrocellulose) may reduce scattering, allowing excitation gentle to penetrate farther, and emission light to exit from deeper within a substrate or membrane. The index of refraction of the liquid or miscible combination of liquids may be within…