Lead Investigators

Jack Judy, Tom Harmon

Overview

Although many sensors are commercially available (e.g., seismic, meteorological, acoustic), small, inexpensive, and high performance sensors for other critical measurands are not (e.g., chemical and biological). Thus, the sensor group will only emphasize important CENS sensors and sensor-related technologies currently not available from the market. For example, for the last three years, we have focused on developing sensors for soil. These applications require an array of miniaturized chemical sensors to accurately monitor the flow of contaminants in environmental media. Nitrate was identified as a critical molecule to detect in a number of different applications, and so we have developed several novel technologies that cover a broad range of nitrate sensitivity from ~ppm to ppb. Two of these are ready to be packaged for field deployment: a potentiometric sensor that uses nitrate-doped electropolymerized pyrrole on carbon fibers, and a micro-machined amperometric nitrate sensor with partially integrated and assembled microfluidics. Using prototypical PPy-coated microfibers, we have directly measured nitrate concentrations in residual soil water found in soil previously irrigated with recycled wastewater (the first known direct assessment of nitrate concentrations in residual soil moisture of its kind) and have observed local nitrate concentrations in surface sands at the Palmdale experimental irrigation site.