Several US agencies and regulators require low-cost chemical sensors for detecting and monitoring environmental clean-up, remediation, and decommissioning processes where groundwater may be contaminated. The sensors must be capable of detecting contaminants in the sub-surface groundwater and must be compatible with use in a range of environments. Most significantly, these customers require a low-cost alternative to its current expensive and labor intensive methods, namely using mobile laboratories. The project will result in the innovative use of low-cost sensor systems that will be capable of detecting and monitoring for dense non-aqueous phase liquids in the subsurface and groundwater, unattended, and in real- time from within a push-probe, using a chemicapacitor array and miniature preconcentrator. The ultimate goal of this SBIR project is to provide the DOD, DOE, and other agencies with a method to map and track subsurface contamination plumes in real-time without requiring an operator. In Phase I, Seacoast successfully demonstrated the feasibility of using a microsensor array with a proprietary trap-and- purge preconcentrator to detect chlorinated solvents, specifically TCE, and TCA, at levels low enough to meet EPA mandated levels for drinking water. In Phase II Seacoast proposes to improve the selectivity and sensitivity of the system to better meet the needs identified by the Phase I consultant. The systems have MEMS microcapacitor sensor arrays that can monitor for leaks of toxic chemicals, contaminants from wastes, and changes in groundwater streams. A preconcentrator traps the contaminants and releases them to a microsensor array. These sensor arrays are filled with several chemoselective polymers whose dielectric permittivity changes when exposed to different vapors, creating a fingerprint response for each chemical. In Phase II Seacoast will specifically develop new materials to improve the sensor array selectivity, 1) by using impedance spectroscopy to study the mechanisms by which the polymer-based sensors sorb the target chemicals, 2) by implementing pattern recognition algorithms to identify chemicals for the sensor responses, and 3) by designing new preconcentrator materials that can bind these chemicals more strongly. The most important application to public health and safety is unattended monitoring of drinking water, water treatment processes, and water sources. Potential markets include building chemical process monitoring and control, toxic vapor leak detection, industrial process control, and industrial health and safety. Transitioning the developed prototype to other markets where worker and public health, environmental health and regulatory compliance will be investigated to reduce the financial risks and broaden the acceptance of the technology.
This proposal describes a novel technology that specifically addresses the need for detecting groundwater contaminants and long-term monitoring of contaminated sites, by providing an unattended sensor system that tracks contamination in real-time and transmits contaminant concentrations. Such a system would be used in tandem with other methods, to provide comprehensive contamination management at DOE, DOD, and Superfund sites where ground and water clean-up projects are already underway. The proposed work will focus on detection of chlorinated hydrocarbons, which are described as among the most common pollutants in groundwater and soils at DOE sites.
