In-Situ Measurement of Vehicle Exhaust Emissions Using SupramolecularConducting Polymer Films

New approaches are needed for the measurement of CO, NOx, SO2, aromatic hydrocarbons (i.e., butane, benzene, toluene, and xylene), and particulate emissions associated with mobile sources. With the constant increase in motor vehicle use, there is a need to develop cost-effective, rapid, and inclusive techniques for monitoring emissions from motor vehicles. A viable air-monitoring system, sensor, device, and/or technique must detect the gases mentioned above selectively at environmentally relevant concentrations. This research project will focus on the use of highly organized conducting polymers and/or conducting polymer/inorganic oxide and conducting polymer-doped metal nanocomposites with high conductivity, which will selectively recognize the above pollutants. The layer-by-layer self-assembly technique will be utilized to fabricate films of conducting materials. Fractal Systems, Inc., proposes to develop highly sensitive, cost-effective, and reliable sensors for the in-situ measurement of pollutants produced by motor vehicles. With the expected high selectivity, low detection limit, and online monitoring of the exhaust gases, the proposed project will result in devices that will perform in situ measurements in the real world. During Phase I, highly ordered nanoscale films will be synthesized in various layer thickness. These films will be characterized using several techniques, particularly conductivity measurements, as the films are subjected to various levels of different gases separately for calibration towards devising the sensors. Mixtures of gases will be used for selectivity studies in the designed sensor chip. In Phase II, optimization of materials and techniques will be addressed together with scale-up designs and commercialization of the technology. It is anticipated that gas selectivity will be easily achieved, because each of the conducting polymers will have a different recognition factor for each gas. It also is anticipated that detection limits for each pollutant will exceed U.S. Environmental Protection Agency (EPA) standards, due to the novel architecture of the electrode material, the controlled nanoscale layer thickness, and the designed chip. Anticipated benefits of the proposed sensors consist of monitoring air quality through detection of gases that typically emanate from exhausts of motor vehicles. The same pollutants can arise from man-made pollution (i.e., industrial plants) as well, and therefore need to be monitored to ensure levels are below EPA specifications, ensuring good air quality. Considering the low cost of the procedure, the market is expected to be significant, with the initial users being EPA, state and local monitoring agencies, and private automobile-testing organizations.