A Low-cost Handheld Sulfur Dioxide Tester with a Hybrid Nanomaterials-based Sensor Chip

This SBIR Phase II project aims to further advance the progress made during phase I toward the development of a portable handheld detector for real-time onsite detection of sulfur dioxide (SO2). SO2 is an air pollutant, which can adversely affect respiratory and cardiovascular health in humans. Onsite monitoring of SO2 would enable real-time detection of chronic and acute exposure to this toxic gas and lead to the mitigation of health problems. Currently, large stationary expensive UV-fluorescence analyzer equipment can be used to monitor SO2 levels in the ppb range, but this makes it difficult to monitor levels of SO2 at many different locations. Therefore, there is a need for a portable and inexpensive SO2 detector to expand the areas where monitoring is possible. This would assist in limiting exposure to this toxic gas. Electrochemical SO2 detectors meet some of these requirements but have poor sensitivity and insufficient detection concentration ranges to meet EPA standards for monitoring SO2.NanoAffix has expertise related to developing graphene-based sensors for monitoring water and air quality. The sensors for SO2 detection utilize graphene coated with mixed metal oxide nanoparticles which are being optimized for sensitivity and selectivity toward measuring SO2 onsite. This innovation combines the excellent electronic properties of graphene with the selectivity of novel mixed oxide nanoparticles for SO2 detection. These sensors function as chemiresistors and are capable of portable and inexpensive detection of SO2 in the necessary single digit ppb concentration range under ambient conditions. In phase I, NanoAffix demonstrated sensitivity down to 2 ppb SO2 under ambient temperature and pressure with these graphene-based sensors. NanoAffix successfully created a calibration curve in the range of 2 ppb to 40 ppb SO2 for detecting unknown concentrations of SO2. The gas sensor market size is estimated to be $4.7 billion by 2025 according to ‘Global Gas Sensors, Detectors, and Analyzers Market Report 2019-2025’ by Frost and Sullivan. At the conclusion of this phase II project, NanoAffix intends to have a commercially viable portable tester with a proprietary calibration algorithm and innovative sensors coated with novel and proprietary mixed metal oxide nanoparticle probes for detecting SO2.