Abstract. Species-level Identification of Pathogenic Viruses on a Microfluidics Platform Radiation Monitoring Devices, Inc. (RMD) proposes to develop a field-portable, low power and inexpensive instrument for the identification of pathogenic viruses which are collected by an aerosol concentrator. It will incorporate modular, microfluidic platforms to capture and concentrate the sample for a rapid, two-stage analysis. The first employs pathogen capture on antibody decorated, paramagnetic nanospheres and will provide rapid, preliminary warning based on the hydrodynamic properties of the nanoparticles when the targeted viruses are bound. This stage will monitor the relaxation of their magneto-optical birefringence and will trigger an alarm when the birefringence relaxation rate drops off dramatically. The methodology allows for continuous surveillance over virtually unlimited periods. The second stage will provide either confirmation or correction to the preliminary identification. It is based on the ability to interrogate the captured viral genome with molecular beacon probes which become fluorescent when they hybridize with specific nucleotide sequences. The biosensor will integrate the two stages of sample transfer, preparation and analysis in a microchannel architecture. Employing both proportional mode Avalanche Photodiode (APD) detectors and Geiger-mode pAPDs in array format, high throughput with parallel processing of multiple probes is possible. Sensitivity to low virus titers is afforded by the single photon sensitivity of these detectors. The proposed viral typing instrument will fill the void in field portable instruments that are available for both military and civilian assessment of pathogen risk.