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Convergence of sensor technologies into a tool for assessing environmental contaminants


OBJECTIVE: Design, develop and demonstrate the integration existing and developing methods for passive sampling, qualitative and quantitative sensing, and reporting in a single convergent environmental micro-scale sensor. This technology should"push"for a low cost rapidly deployable sampler for contaminant assessment in water, soil, or sediment to include multiple analytes such as hydrophobic organic compounds, metals, and microbes. DESCRIPTION: The U.S. Army requires methods for rapidly sampling and analyzing chemical and biological contaminants as part of combat mission, engineering support, or in support of humanitarian or disaster response missions (Army 2012). Sensing contaminants is required to identify potential environmental threats, be used to identify areas where contamination is most significant, and guide soldiers and technicians to areas and contaminants that require further investigation. To date, the greatest challenge for sensors has been to combine the sensing, detecting, and reporting methods into a single convergent device. Current sensor technology research has not overcome the challenges required to field a functioning reliable and sensitive sensor to meet these requirements. These challenges include incorporating the sampler and sensing device in a platform that also includes a reporting element. For example, it is expected that advances in microelectromechanical systems (MEMS) will provide opportunities to meet this requirement. Further challenges that will require ongoing research include fouling of sensors, reliability testing, accuracy of the sensor, size/portability of the sensor, and shelf life prior to use (Farahi et al., 2012). The current approach to detecting environmental contaminants continues to be based on the collection and shipping of field collected samples to a laboratory for analysis; a task that often requires over 30 days to obtain quality usable data to guide decision making. The vision for this sensor is to combine sampling and sensing technologies such as a ruggedized MEMs device. The sensor will be used in the field and must be small (<5 cm2,<100 g), rugged, self-contained, easy to deploy, easy to interpret, and not require continuous monitoring. An ideal sensor could be deployed over longer periods of time (up to 4 weeks) and report when contamination is present. PHASE I: Combine innovative and developed approaches for sampling and sensing contaminants. Sampling methods should consider approaches for concentrating the sample for detection through adsorption or through fluidic processes (Conder, 2003). The sensor should consider novel methods for sensing the compounds of interest in a qualitative (present/not present) or semi-quantitative (low, medium, high) manner. Demonstrate a proof of principle of the proposed design and preliminary demonstration in the laboratory. Successful demonstration will include sensing and reporting and meet the criteria listed above. PHASE II: Develop and demonstrate a prototype that can be tested in the field and further optimized to address issues such as interference, fouling, sensitivity, error, and reporting. The sensor must be capable of detecting multiple chemicals of concern simultaneously. Demonstration should include an iteration and feedback from technical Army users of the technology. Conduct testing to demonstrate feasibility of the component for use with ongoing development of sensing kits currently being developed within ERDC. PHASE III: The technology developed under this effort includes development for dual use applications in military and civilian areas related to environmental protection. Response to spills requires methods to determine the extent and quantity of contamination in order to make decisions about risk and direct limited resources for emergency clean up. For example, the response to the Deepwater Horizon could have been greatly accelerated and improved with real time analysis of organic contamination from the spill. Local, county, state and federal emergency spill teams can also use this capability and technology for emergency response from accidents. This capability can also be used by industry to enable an improved rapid analysis capability for cleanup at contaminated sites. REFERENCES: 1. Army 2012. Army 6.2/6.3 Leap Ahead Workshop. Ft Dietrick, MD. 2. Farahi R.H., Passian A., Tetard, L., and Thundat T. 2012. Critical issues in sensor science to aid food and water safety. ACS Nano. 6(6): 4548-4556. 3. Conder J. M., La Point T. W., Lotufo G. R., and Steevens J. A. 2003. Nondestructive, minimal-disturbance, direct-burial solid-phase microextraction fiber technique for measuring TNT in sediment. Environmental Science and Technology, 37 (8): 1625-1632. 4. (RD) 230 Chemical Exposure Guidelines for Deployed Military Personnel.
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