Abstract: A novel adaptation of surface plasmon resonance based protein detection technology is presented: Confined-Surface Plasmon Resonance Imaging (Confined-SPRi). Confined-SPRi is capable of tracking label-free protein separation in real-time throughout micro/nanofluidic channel devices. In this way, protein behavior can be continuously monitored as the proteins progress through each stage of the fluidic device such that in situ routing or extraction of desired protein groups is possible. Although continuous protein tracking may be possible with the attachment of fluorescent labels, Confined-SPRi is powerful in that it accomplishes this task label-free such that proteins remain in their natural, unmodified state. This capability greatly benefits the field of protein research by relaxing the cost and technical burden of label usage, providing more insight into natural protein behavior, and streamlining analysis. Other label-free separation detection technologies exist, but they have limited utility as they are best suited for post-separation analysis at the channel exits. Confined-SPRi is based upon the unique integration of capillary electrophoresis (CEP) with surface plasmon resonance imaging (SPRi). For integration to be successful, the SPR sensor should be shielded from the damaging electric fields generated for CEP separations, but still be capable of sensing separation events in the bulk of the channels. Since achieving this integrated capability is contrary to the common application of SPR technology, several key modifications were developed to make this possible. These modifications included dividing the sensor into small segments (200 x 200 μm squares with 8 μm spacing), coating the sensor with a thin protection layer (30 nm thick layer of CYTOP perfluoro-polymer), and confining the fluidic channels to within the SPR sensing reach (∼500 nm). Data is presented showing the separation of proteins using both zone electrophoresis and moving boundary electrophoresis. Sources of dispersion also were evaluated in order to provide direction as to where future improvements on the technology should be focused.