Environmental sampling systems to improve sensor selectivity, sensitivity, and versatility
- Sandia National Laboratories, Albuquerque, NM (United States)
Environmental sensor systems are needed for a variety of applications including field screening, site characterization, process monitoring, waste characterization, and exhaust monitoring. The performance of environmental sensor systems in the field is often determined by considerations such as thermally-induced sensor drift and humidity-induced sensor responses, rather than by the short term noise level of the sensor often used to estimate detection levels based on laboratory evaluations. This observation has held true in the development of portable acoustic wave sensor (PAWS) systems for volatile organic compounds (VOCs). These systems use polymer-coated surface acoustic wave (SAW) sensors. SAW devices are very sensitive to changes in the mass or viscoelastic properties of a coating formed on the device surface. The rapid absorption and desorption of VOCs into rubbery polymer coatings enables rapid, real-time analysis. However, even though uncoated SAW devices can be fabricated with low temperature coefficients, the change in polymer viscoelastic properties with temperature results in significant temperature sensitivities for coated sensors. A key advantage of a SAW sensor is its ability to detect mass changes, enabling its use for detecting any chemical bound to the surface (all species have mass). This advantage has a down side in real-world applications since water adsorbs on any surface resulting in small but detectable humidity responses.
- OSTI ID:
- 441303
- Report Number(s):
- CONF-960782-; TRN: 96:006557-0074
- Resource Relation:
- Conference: 6. international meeting on chemical sensors, Gaithersburg, MD (United States), 22-25 Jul 1996; Other Information: PBD: 1996; Related Information: Is Part Of The 6th international meeting on chemical sensors; PB: 313 p.
- Country of Publication:
- United States
- Language:
- English
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