SBIR Phase II: Fast-Response, High Sensitivity MEMS based NOx Emission Sensor

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This Small Business Innovation Research (SBIR) Phase II project will develop a nitrogen oxide (NOx) sensor for diesel engine and other lean-burn combustion systems. This innovation combines unique SiC-based piezoelectric bimorph microresonator chemical detection technology with NOx sensitive materials, to develop an emissions control NOx sensor capable of operating in harsh engine emissions environments. The feasibility of the NOx sensor was demonstrated in Phase I by assembling a preliminary prototype, testing it in environments characteristic of hot engine emissions, and demonstrating 1 ppm NOx detection with 1 second response times and stable operation at 400?aC. The Phase II research objectives are to refine the sensor, including the bimorph resonator, NOx sensitive coatings, packaging and control electronics, to achieve higher temperature operation, 5 year lifetime, and reliable detection of 1 ppm NOx in the presence of varying concentrations of other exhaust gases. Extensive stability and life testing will be performed to identify and address potential degradation mechanisms such as poisoning, fouling, carbon deposition and materials inter diffusion. The prototype, including integrated heater, temperature sensor, control electronics and power/ data interface, will be operated in engine test stands to demonstrate performance in actual exhaust environments. The broader impact/commercial potential of this project lies in its ability to accelerate the adoption and use of automobiles that use clean diesel and renewable diesel fuels, which is a low-risk and high-impact way of reducing both polluting emissions and US dependency on foreign energy supplies. Diesel engines typically produce up to 20% less greenhouse gas emissions than a comparable gasoline powered vehicle. However, they also produce a significantly higher amount of nitrogen oxides (NOx), a pollutant that causes smog and acid rain. Although the technology exists to treat and eliminate this NOx pollution, it requires a high temperature compatible sensor with sensitivity and response time that does not exist commercially today. This NSF SBIR Phase II program will develop a NOx sensor capable of meeting the needs of the automotive industry for a diesel engine emissions sensor for both real-time on-board diagnostics and emissions reduction, bringing vehicles into compliance with new environmental regulations coming into effect in 2013. Enabling the wider adoption of clean diesel engines will reduce both greenhouse gas emissions and dependency on petroleum, as consumers increasingly choose these greener and more cost-effective vehicles.