SPR-CPI integrates the real-time label-free detection capabilities of surface plasmon resonance (SPR) with the sensitivity and environmental drift stability of common-path interferometry (CPI) to yield an analytical instrument with unsurpassed performance attributes. SPR-CPI is a platform technology that enables true multiplex array detection capacities at sensitivity levels previously achieved only with single-channel systems. Application-specific consumable biochips with 1-150 features per chip are used on the instrument, and can be user-customized for specific intermolecular interaction analysis. SPR-CPI’s unique use of phase-based image analysis will revolutionize molecular detection science and simplify currently deployed methods to reduce operational cost and labor input. The instrument’s only moving parts are the pumps that circulate analyte. Applications of SPR-CPI technology include any analytical system that relies upon molecular interaction. Specifically applicable markets include: Biological warfare agent detection, nucleic acid analysis, antibody/antigen systems, infectious disease screening for both bacterial and viral targets, personalized medicine, and pharmaceutical and academic research.