INFRNO2: INfrared Faraday Rotation of NO2 for Portable Sub-Part-Per-Billion Sensors

This Small Business Innovation Research Phase I project focuses on the development of a proof-of-concept ultra-portable nitrogen dioxide (NO2) sensor based on mid-infrared quantum cascade laser (QCL) spectroscopy. NO2 is a critical air pollutant which can trigger respiratory/cardiovascular disease and new standards by the National ambient Air Quality Standards (NAAQS) limit 1 hour concentrations of NO2 to 100 parts-per-billion (PPB). An ultra-portable, lower power consumption sensor for NO2 will enable easy-to-deploy sensor networks for NO2. However NO2 is a difficult gas molecule to measure at low cost and portable form-factor, especially when measurements require lt 0.1 pbb sensitivity. Phase I will explore the development of components suitable for a low power consumption (potentially<6W), autonomous, shoebox sized, laser spectroscopic NO2 sensor with better than 0.1 ppb precision in 1 second for wireless sensor networks (WSNs) using novel high-efficiency infrared QCLs. The sensing method will based on Faraday rotation Spectroscopy using electro- and rare-earth magnets, multipass cells, and mid-infrared QCL, which provides and possibilities of robust, low power consumption, and low maintenance operation. The broader/commercial impact of this work targets improved air pollution monitoring for public health. This will be greatly beneficial to society since illnesses such as asthma, heart disease, autism, diabetes, and cancer may have air quality triggers, and NO2 concentration can be linked to general air quality. This work directly addresses the need of NO2 roadside air quality monitors desired by regulatory agencies. When fully mature, the technologies developed in this work will have the capability to sense other critical pollutant and greenhouse molecules, providing novel monitoring technologies for a wide variety of pollutants. These sensors place in a WSN will provide more powerful capabilities than other gas quantification and localization techniques by measuring directly at the sources and at multiple points, providing high spatio-temporal resolution over wide areas. Absolute verification over wide areas coupled to epidemiological data will provide new insights into health impact of air pollution, and allow regulatory agencies to monitor emissions more efficiently. Additionally, these sensors will be able to directly verify concentrations without human intervention, enabling verified air pollution trading markets designed to lower emissions over time.