In Situ Metal Ion Sensors for Monitoring and Control of Nutrient Solutions

This Phase I proposal addresses the need to develop in situ, multi- element sensor arrays for nutrient solution analysis. Various macrocycle compounds have been shown to uniquely complex metal ions. The innovation is to use chromogenic macrocycle compounds, which are currently under development, and optical transduction principles, to fabricate and test metal ion sensors. The Phase I work includes fabrication of these recognition elements; attachment to optical substrates; and spectrophotometric characterization in the presence of select metal ions to determine sensitivity, response time, reversibility, linearity and stability. Preliminary evaluation in multicomponent and mixed metal solutions will be performed in Phase I. Simple, reliable, in situ sensors to monitor dissolved metal ions do not exist at present. In a Phase II effort, a prototype Metal Ion Sensor Array will be fabricated, tested, and delivered to NASA for evaluation in a Nutrient Delivery System. This sensor system could also be used to assure the quality in water reclamation systems currently under development by NASA for use in long- duration space flight, and could be used as part of a mobile robotics laboratory for exobiology experimentation and sampling.