Nitride-Based Microarray Biochips: A New Route of Plasmonic Imaging

The desire to improve human lives has led to striking development in biosensing technologies. While the ongoing research efforts are mostly dedicated to enhancing speed and sensitivity of the sensor, a third consideration that has become increasingly important is compactness, which is strongly desired in emergency situations and personal health management. Surface plasmon resonance imaging (SPRi) is one of the few techniques that can potentially fulfill all the three goals, considering its multiplexed assay capability. However, miniaturizing SPRi biosensors remains elusive as it entails complicated optical gears. Here, we significantly slim the architecture of SPRi devices by visualizing the varied local density of states around analytes. The unusual detection scheme is realized by building a gain-assisted SPRi with InGaN quantum wells (QWs), where the QW-plasmon coupling efficiency hinges on localized refractive index variation. This new modality abolishes the prism, the polarizer, and the beam-tracking components in the most used Kretschmann configuration without compromising the performances.