Mixed-Potential Based Miniature Sensors for Real-Time On-Vehicle NOx Monitoring From Mobile Sources

EPA Contract Number: 68D03061
Title: Mixed-Potential Based Miniature Sensors for Real-Time On-Vehicle NOx Monitoring From Mobile Sources
Investigators: Nair, Balakrishnan
Small Business: Ceramatec Inc.
EPA Contact: Manager, SBIR Program
Phase: II
Project Period: October 1, 2003 through December 31, 2004
Project Amount: $224,979
RFA: Small Business Innovation Research (SBIR) - Phase II (2003) Recipients Lists
Research Category: Air Quality and Air Toxics , SBIR - Air Pollution , Small Business Innovation Research (SBIR)


Nitric oxide and nitrogen dioxide (jointly represented as NOx) constitute one of the primary pollutants in engine exhaust from mobile sources such as diesel trucks. Monitoring the NOx concentration is critical for the application of new control technologies for the reduction of NOx to meet new U.S. Environmental Protection Agency (EPA) emissions regulations that become effective in 2007. Current sensor technologies do not have adequate performance in the expected high-temperature operating conditions. The goal of the Phase I research project was to demonstrate the feasibility of using a novel mixed-potential based miniature sensor that has high-temperature capability, high sensitivity, fast response time, and very little cross-sensitivity with other exhaust gas constituents.

During Phase I, the technical objectives were successfully achieved, Ceramatec, Inc., demonstrated that a NOx sensor is capable of operating in the high-temperature environment typical of exhaust gas (550°C). In addition, a novel catalyst system was developed that enabled Ceramatec, Inc., to eliminate the cross-sensitivity between NO and NO2, and minimize cross-sensitivity to other gases commonly found in exhaust, such as CO, CO2, H2O, and SO2. This resulted in the ability to obtain a meaningful output signal for measurement of the total NOx concentration in a gas mixture that simulates diesel engine exhaust. Finally, a 90 percent response time of about 1 second was demonstrated, thereby showing the feasibility of using this sensor as part of a control system.

During Phase II, Ceramatec, Inc., will perform sensor optimization and prototype development of sensors to prepare for Phase III commercialization. The Phase II research project will involve optimization of the sensor design to: (1) minimize the 90 percent response time to the desired value of less than 500 milliseconds, (2) perform optimization of sensor processing to obtain sufficient statistical information to establish a manufacturing process, and (3) perform long-term testing of the prototypes in simulated operating conditions.

Because the proposed sensor will allow online monitoring of NOx concentrations in mobile sources, allowing for real-time process modification, it will enable highly efficient NOx emissions reduction. Thus, the successful development of this technology will result in significant NOx emissions reductions from mobile sources. It is estimated that compliance with new EPA regulations can lead to a reduction of up to 686,000 tons of NOx per year by 2010. It also is anticipated that because of the collaboration of Ceramatec, Inc., with a diesel engine manufacturer from the start of the research project, the potential for commercialization of the technology has been greatly enhanced.

Publications and Presentations:

Publications have been submitted on this project: View all 2 publications for this project

Supplemental Keywords:

small business, SBIR, EPA, NOx, CO, CO2, H2O, SO2, emission measurement technology, mixed potential, sensor, exhaust stream, catalyst system, mobile sources, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, RESEARCH, particulate matter, Air Quality, air toxics, Environmental Chemistry, Monitoring/Modeling, Analytical Chemistry, Monitoring, mobile sources, Environmental Monitoring, Atmospheric Sciences, Engineering, Chemistry, & Physics, Environmental Engineering, ambient aerosol, ambient air quality, Nox, remote sensing, Nitrogen Oxides, atmospheric measurements, ambient particle properties, vehicle emissions, atmospheric particles, aerosol particles, motor vehicle emissions, NOx control, diesel particulates, automotive emissions, airborne particulate matter, diesel exhaust particulates, diesel exhaust, emissions, air sampling, atmospheric aerosol particles, PM, diesel exhaust particles, real time monitoring, aersol particles

Progress and Final Reports:

  • Final Report

  • SBIR Phase I:

    Mixed Potential-Based Miniature Sensors for Real-Time On-Vehicle NOx Monitoring From Mobile Sources  | Final Report