Grantee Research Project Results
Final Report: Wireless Decontamination Gas Monitor
EPA Contract Number: EPD05038Title: Wireless Decontamination Gas Monitor
Investigators: Mlsna, Todd
Small Business: Seacoast Science, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: March 1, 2005 through August 31, 2005
Project Amount: $66,204
RFA: Small Business Innovation Research (SBIR) - Phase I (2005) RFA Text | Recipients Lists
Research Category: SBIR - Homeland Security , Small Business Innovation Research (SBIR)
Description:
There is a growing threat of biological warfare agents (BWA) against U.S. civilian and military targets (i.e., the Hart Senate Office Building). Part of the decontamination process following a BWA event involves fumigation with chlorine dioxide (ClO2) and hydrogen peroxide (H2O2). These chemicals kill the agent but cause no damage and leave no chemical trace. Accurate fumigant concentration monitoring is an essential element of a well-balanced tactical approach to efficient remediation following a BWA event. A detection system employed at fumigation sites must not only wirelessly report the presence, but also the distribution, and preferably the concentration, of the chemical fumigant back to a central control unit. Seacoast Science, Inc., has provided proof-of-concept technical results and a proposed prototype design for the detection of ClO2 and H2O2 for use in the cleaning process after fumigation. The proposed sensor system consists of an array of chemoselective polymers coated onto microelectromechanical systems chemicapacitors, a radio, and a user interface. Seacoast Science’s sensor technology utilizes an array of micromachined capacitors, coated with chemoselective materials selected for their sensitivity to the fumigation chemicals.
Summary/Accomplishments (Outputs/Outcomes):
Optimization of Chemoselective Polymers
Chemoselective polymers were successfully synthesized and characterized against interferents and fumigants, functionalized polysiloxanes, polycarbosilanes, and gold nanoparticles. Commercial polymers also were characterized against interferents and/or fumigants.
Characterize the Phase I Prototype Using These Fumigants and Potential Interferents
Sensor arrays with proprietary and commercial chemoselective materials were developed. The change in capacitance of these arrays against interferents (water, acetone, ethanol, and octane) and fumigants (H2O2, ClO2) was determined. Gold nanoparticles functionalized with an alkyl thiol containing a linear alkane spacer and a linear alkane ester end group respond irreversibly to H2O2. A commodity polymer containing oxygen in the main chain with a pendant halogen was shown to reversibly respond to ClO2 vapor generated by the aqueous oxidation of sodium chlorite by sodium persulfate.
Characterize the Requirements of a Sampling System
Seacoast Science continued a collaboration with the Naval Research Laboratory on the utilization of a cascade avalanche sorbent plate array (CASPAR) preconcentrator. Research and development of a proprietary preconcentrator is underway. The CASPAR preconcentrator was shown to marginally enhance the detection of OP and will have to be further modified for use in a fumigant detector.
Radio Optimization for Low-Power and Transmission-Only Operation
A detector prototype was fabricated based on the microcapacitor sensor systems currently being developed by Seacoast Science. A commercial system transceiver and low-power microcontroller have been incorporated in the circuit to process the sensor data. The microcontroller provided a custom-designed, error-correction protocol compatible with the company’s SC-200 sensor data stream. A test of the range and error rate of the transceiver, with very low data rate, was performed in Seacoast Science’s laboratory and found to be satisfactory.
Conclusions:
This Phase I research project established the viability of Seacoast Science’s capacitive sensors by demonstrating detection of two classes of fumigants. This was accomplished through the preparation of new sensor designs and the synthesis and testing of new chemoselective polymers, network materials, and organometallic compounds. Micromachined, parallel-plate capacitors can be filled with the aforementioned materials and used to detect H2O2 and ClO2. Chemicapacitors are unique among polymer-based sensors in that they offer selectivity due to the characteristic electrical properties of the analyte, in addition to the selective sorption due to the polymer/analyte interactions. This unique sensitivity of chemicapacitors to analyte permittivity may lead to sensor systems with improved selectivity. In addition, smaller gaps lead to thinner polymer films and, therefore, faster response. The project also demonstrated the successful integration of a commercial radio transmitter and redesign of Seacoast Science’s system to minimize power. Further research and development into the sensor design, chemoselective materials synthesis, and pattern recognition will result in a sensor capable of detecting ClO2 and H2O2 vapors for potential applications in building remediation (in response to a BWA attack or mold infestation) and in the food industry.
Supplemental Keywords:
safe buildings, chlorine dioxide, ClO2, hydrogen peroxide, H2O2, biological warfare agents, BWA, sensor system, chemoselective polymers, microelectromechanical systems chemicapacitors, fumigant, interferent, cascade avalanche sorbent plate array, CASPAR, preconcentrator, nanoparticles, microcapacitator, microcontroller, organometallic compounds, building remediation, mold infestation, food industry, EPA, small business, SBIR,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Environmental Chemistry, Monitoring/Modeling, Environmental Monitoring, Environmental Engineering, Engineering, Chemistry, & Physics, gas detector, homeland security, building decontamination, chemical characteristics, field portable monitoring, gas monitoring, human exposue, air sampling, chemical composition, chemical detection techniques, chemical microsensors, gas sensing system, chemically sensitive interfaces, microelectric mechanical systems chemicapacitor technology, chemical attackThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.