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 (mid-IR QCL) spectroscopy. NO2 is a critical air pollutant that can trigger respiratory/cardiovascular disease, and new standards under the National Ambient Air Quality Standards (NAAQS) limit 1 hour concentrations of NO2 to 100 parts-per-billion (ppb). An ultra portable, low-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 formfactor, especially when measurements require < 0.1 ppb 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 be based on Faraday Rotation Spectroscopy (FRS) using electro- and rare-earth magnets, multipass cells, and a mid-IR QCL, which provides the 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 beneficial to society because illnesses such as asthma, heart disease, autism, diabetes and cancer may have air quality triggers, and NO2 concentrations can be linked to general air quality. This work directly addresses the needs 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 gas molecules, providing novel monitoring technologies for a wide variety of pollutants. These sensors placed in a wireless sensor network (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 across wide areas. Absolute verification across 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. Supplemental
Keywords: air pollution, air pollution monitoring, nitrogen dioxide, quantum cascade laser, portable, sensor, mid-infrared quantum cascade laser, QCL, emissions
