Center for Embedded Network Sensing

Nitrate pollution of groundwater is often the result of non-point sources of nutrients or livestock waste. Thus, the notion of a technology that would enable us to efficiently yet economically monitor for nitrate in a distributed fashion is an attractive one. Taking into account the advantages of potentiometry as an electroanalytical method, many efforts have been undertaken to develop reliable ion-selective electrode (ISE) suitable for the determination of nitrate at low concentrations while exhibiting good selectivity for nitrate over potentially interfering anions (chloride, nitrite, hydrocarbonate, perchlorate, thyocyanate and etc.). This work reports on the development and applications of a stable solid state nitrate microsensor based on doped polypyrrole films. We have developed a miniature and inexpensive nitrate sensor by electropolymerizing pyrrole on a surface of pencil leads, using nitrate as a dopant. Pencil leads were found to be a good substitute to expensive conductive materials, such as glassy carbon and platinum.