 These measurements can be used to infer conformational information about the molecular interactions taking place, as the molecule size (from the layer thickness) and the fold density (from the RI) change.DPI is typically used to characterize biochemical interactions by quantifying any conformational change at the same time as measuring reaction rates, affinities and thermodynamics.The technique is quantitative and real-time (10 Hz) with a dimensional resolution of 0.01 nm.