tailieunhanh - Volatile Organic Compound Detection Using Nanostructured Copolymers

Consequently the chemical contamination builds to higher levels in these organisms. Indigenous peoples in the Arctic, whose traditional diets are heavy in fatty foods and who often have no alternatives for nourishment, thus have some of the highest recorded levels of POPs. Yet they are hundreds or thousands of kilometres from where these pesticides and industrial chemicals were released, and they certainly received little benefit from the chemicals' original use. The Stockholm Convention addresses the challenge posed by these toxic chemicals by starting with 12 of the worst POPs ever created. Nine of the POPs are pesticides: aldrin, chlordane, DDT (famous for decimating bald eagles, ospreys,. | Volatile Organic Compound Detection Using Nanostructured Copolymers NANO LETTERS 2006 Vol. 6 No. 8 1598-1602 Bo Li 1 Genevieve Sauve 4 Mihaela C. Iovu Malika Jeffries-EL Rui Zhang Jessica Cooper Suresh Santhanam Lawrence Schultz Joseph C. Rovelli Aaron G. Kusne Tomasz Kowalewski Jay L. Snyder 1 Lee E. Weiss Gary K. Fedder Richard D. McCullough and David N. Lambeth Electrical and Computer Engineering Department Chemistry Department Robotics Institute and Chemical Engineering Department Carnegie Mellon University Pittsburgh Pennsylvania 15213 and National Personal Protective Technology Laboratory National Institute for Occupational Safety and Health Pittsburgh Pennsylvania 15236 Received March 3 2006 Revised Manuscript Received June 2 2006 ABSTRACT Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as the active layer in volatile organic compound VOC chemresistor sensors. While the regioregular polythiophene polymer chain provides a charge conduction path its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a block copolymer or by making a random copolymer of polythiophene with different alkyl side chains. The copolymers were exposed to a variety of VOC vapors and the electrical conductivity of these copolymers increased or decreased depending upon the polymer composition and the specific analytes. Measurements were made at room temperature and the responses were found to be fast and appeared to be completely reversible. Using various copolymers of polythiophene in a sensor array can provide much better discrimination to various analytes than existing solid state sensors. Our data strongly indicate that several sensing mechanisms are at play simultaneously and we briefly discuss some of them. The demand for low-cost low-power and portable volatile organic compound VOC detection is increasing dramatically due to the need for .