Detection, sizing, and shape identification of single nanoparticles and viral pathogens

Detection of single nanoscale particles, in particular viral pathogens, have been a challenging task with earlier efforts focusing on high-Q resonators to overcome the sensitivity limitations of conventional optical techniques. We have developed a new biodetection technique - Interferometric Reflectance Imaging Sensor (IRIS) originally for protein microarrays in multiplexed molecular diagnostics. Recently, we have demonstrated that a multi-LED discrete wavelength illumination system can substitute for the tunable laser in IRIS technology. Broad spectral coverage afforded by the use of multi-color visible LEDs allow for not only a compact, battery-operated, and portable system, but also enables the use of very thin transparent layer in IRIS substrates and thus high lateral resolution imaging.