Center for Embedded Network Sensing

Many water quality problems would be better understood and more effectively managed if relevant environmental system could be observed overtime in a spatially ditributed manner. Current commercially available chemical sensors are relatively expensive, or are generally not optimally packaged for field deployments. This work examines the potential for use of nitrate selective electrodes in distributed sensor networks in environmental systems. Short-lived popypyrrole-based nitrate selective sensors are fabricated on mechanical pencil lead substrates and tested for selectivity over other environmental anions. Results for these sensors are compared against more expensive commercial nitrate sensors in two soil testbeds under irrigation conditions. The results demonstrate the potential for fabricating numerous inexpensive sensors that are scaleable to applications in distributed environmental observation networks. Discrepancies between larger commercial sensor results and the PPy sensors suggest that more tests are needed to determine the most accurate strategy for coupling sensors with targeted environmental medium. Nitrate-selective mini-sensors with polyvinylchloride membranes have been developed as an attempt to improve sensor lifetime in the field, results of pre-deployment experiments showed that these mini-sensors can be used for field deployments.