Introduced here are interferometric sensors that can be used to conduct biochemical tests. Each interferometric sensor includes an interference layer that is secured along the surface of a monolithic substrate. Analyte-binding molecules can be coated along the surface of the interference layer. Over the course of a biochemical test, a biolayer will form as analyte molecules in a sample bind to the analyte-binding molecules. The refractive index of the monolithic substrate is higher than the refractive index of the interference layer. Moreover, the interference layer may be designed such that its refractive index is substantially similar to the refractive index of the biolayer.