A Low Cost Chemosensor for Measuring Phosphate in Water and Soil

The proposed Phase I SBIR research is expected to lead to the development of a low cost portable instrument capable of making real time measurements of phosphate in water and soil samples. The sensor system for this instrument will be based on the highly selective phosphate binding properties of a co-polymer to be synthesized in this research. In many areas, the rapid growth and intensification of crop and animal farming, including confined animal feeding operations (CAFO), has created regional and local imbalances in phosphorus (P) inputs and outputs. When phosphorus is released into water bodies with adequate nitrogen available eutrophication is likely to result. Eutrophication has been identified as the main cause of impaired surface water quality in the U.S. Concentrations of phosphate in solution are usually small, and time is often a critical factor in taking measurements since the inorganic phosphate in a water sample is changing due to biological processes. Due to these factors, there is a need for sensitive, inexpensive, and portable instruments in order to monitor the eutrophication process effectively. Currently available instruments for making phosphate measurements in the field do not adequately address these needs. The sensor to be developed in this Phase I research will be based on a commercially available microfabricated fringing electric field (FEF) substrate coated with the phosphate-binding polymer. The substrate electrode periodicity will be in the low microns range. By incorporating nanofabrication techniques in the Phase II portion of this research, it will be possible to design and fabricate smaller electrode structures. This will allow us to enhance the sensitivity of the sensor system by tuning the electric field pattern generated by EFE sensor to the dimensions of the proposed phosphate-binding polymer coatings. The key result needed to support the development of a prototype instrument will be the demonstration of binding selectivity for phosphate. A chemosensor, to be developed on the basis of this selectivity, would be relatively inexpensive, would require no chemical reagents, and could easily be installed in the field of continuous and/or remote monitoring applications. It would be a valuable tool which could aid researchers, CAFOs and farmers in the development of improved soil scientists, hydrologists, agronomists, limnologists and animal scientists. Additional commercial opportunities are possible for wastewater treatment process control and other environmental monitoring applications.