Grantee Research Project Results
2001 Progress Report: Development of a Miniature Detector for Accurate Identification of Toxic Environmental Contaminants (DATEC)
EPA Grant Number: R826648Title: Development of a Miniature Detector for Accurate Identification of Toxic Environmental Contaminants (DATEC)
Investigators: Tepper, Gary C.
Institution: Virginia Commonwealth University
EPA Project Officer: Aja, Hayley
Project Period: October 1, 1998 through September 30, 2001
Project Period Covered by this Report: October 1, 2001 through September 30, 2002
Project Amount: $302,268
RFA: Exploratory Research - Environmental Chemistry (1998) RFA Text | Recipients Lists
Research Category: Air , Safer Chemicals , Land and Waste Management , Sustainable and Healthy Communities
Objective:
The objective of this research project is the development of a new chemical sensor technology that will allow identification and quantification of volatile organic compounds (VOCs) in the environment. Special requirements are that the detector must be small, portable, inexpensive, and capable of monitoring the presence of a wide range of atmospheric contaminants.Progress Summary:
In the current year, we finalized the sensor development and characterization activities. Polymer coatings were deposited onto Surface Acoustic Wave (SAW) devices using the technique known as Rapid Expansion of Supercritical Solution (RESS). RESS was shown to be a suitable and robust technique for the development of advanced polymer coatings for miniature chemical sensors. RESS substantially improves coating quality and sensitivity, particularly in the case of polymers exhibiting low permeability. One important aspect of the work was the improvement of sensitivity and response time by increasing the surface-to-volume ratio of the polymer coating.Thin, uniform, reproducible coatings were formed from many different classes of polymers, including those that have proved difficult to deposit using conventional techniques. Coatings were developed from glassy and crystalline polymers and interfaced with SAW transducers. Glassy fluoroalkyl acrylate (FAA) deposited by RESS exhibited three to five times increased sensitivity compared to a coating of similar thickness deposited by air-brushing.
Our results demonstrated that even highly crystalline materials can be successfully interfaced with miniature transducers. A class of materials exhibiting solid-state reactivity was investigated as a potential new sensor coating material. Two diolefinic monomers such as 2,5-distyrylpyrazine (DSP) and diethyl p-phenylenediacrylate (EPA) were deposited in the form of nano-scale particles onto SAW devices and polymerized directly on the surface. These compounds are known to undergo polymerization in the solid-state to a linear polymer with cyclobutane rings in the main chain by UV irradiation. The reaction goes by 2+2 cycloaddition and does not require the use of any additional photoinitiator or catalyst to proceed. The particulate coatings produced by RESS from DSP and EPA polymers were shown to be five times more sensitive than film coatings of a similar thickness deposited by conventional techniques.
Our results demonstrated that increasing the surface-to-volume ratio of polymer coatings improves the sensor response time and sensitivity compared to bulk films of the same mass loading, especially in case of polymers with low permeability. The main reason for this is that the adsorption step of the polymer-analyte interaction increases as the surface area increases, and the permeation length within the coating decreases while the volume (path length) decreases. Therefore, the impact of the polymer permeability on the overall response is minimized.
A novel miniature chemical sensor consisting of an advanced coating deposited by a technique based on supercritical fluid polymer processing interfaced to a microfabricated transducer was developed. The sensor exhibited enhanced sensitivity and response time, particularly in the case of polymers with relatively low vapor permeability.
Future Activities:
The next activities will focus on continuing the optimization of the sensor performance and finalizing the prototype unit with any necessary modifications.Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 24 publications | 3 publications in selected types | All 3 journal articles |
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Levit N, Pestov D, Tepper G. High surface area polymer coatings for SAW-based chemical sensor applications. Sensors and Actuators B-Chemical 2002;82(2-3):241-249. |
R826648 (2001) R826648 (Final) |
not available |
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Pestov D, Levit N, Kessick R, Tepper G. Photosensitive 2,5-distyrylpyrazine particles produced from rapid expansion of supercritical solutions. Polymer 2003;44 (11):3177-3183. |
R826648 (2001) R826648 (Final) |
not available |
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Tepper G, Levit N. Polymer deposition from supercritical solutions for sensing applications. Industrial & Engineering Chemistry Research 2000;39(12):4445-4449. |
R826648 (2000) R826648 (2001) R826648 (Final) |
not available |
Supplemental Keywords:
VOC sensor, atmospheric contaminants, air pollution, VOCs, portable sensor, environmental monitoring., Air, Scientific Discipline, Toxics, Engineering, Chemistry, Environmental Chemistry, Engineering, Chemistry, & Physics, VOCs, Environmental Monitoring, toxic contaminants, air sampling, DATEC, field portable systems, thermally stable polymer film, chemical composition, spectroscopy, chemical detection techniques, field monitoring, analytical chemistry, spectroscopic studies, portable atmospheric contamination detectorRelevant Websites:
http://www.electrochem.org/meetings/past/200/abstracts/symposia/g1/0928.pdf
Progress and Final Reports:
Original AbstractThe 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.