A method is provided for detecting one or more analytes in a sample. The method relies, in part, on the ability of functionalized particles added to the sample to partially or completely inhibit the transmission of electromagnetic radiation into and out of the sample through a detection surface in a reaction vessel containing the sample. In a microarray format, the invention can be used to screen millions, billions or more biological elements, such as an organism, cell, protein, nucleic acid, lipid, saccharide, metabolite, or small molecules. Methods, apparatuses and kits are described.