Methods, apparatus and substrates for the detection of reactions between biomolecules or cells and a second compound are disclosed. The invention detects interactions between ligands and receptors by utilizing detecting the diffusion of a species proximate a sensing area. Absorbance detection and diffraction...http://www.google.ca/patents/US6710877?utm_source=gb-gplus-sharePatent US6710877 - Apparatus and methods for determining biomolecular interactions
