García-Berríos, Edgardo and Gao, Ting and Walker, Don and Brunschwig, Bruce S. and Lewis, Nathan S. (2011) Composites of carboxylate-capped TiO_2 nanoparticles and carbon black as chemiresistive vapor sensors. Sensors and Actuators B: Chemical, 158 (1). pp. 17-22. ISSN 0925-4005 http://resolver.caltech.edu/CaltechAUTHORS:20111108-132622961
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Titanium (IV) dioxide (TiO_2) nanoparticles (NPs) with a 1–5 nm diameter were synthesized by a sol–gel method, functionalized with carboxylate ligands, and combined with carbon black (CB) to produce chemiresistive chemical vapor sensor films. The TiO_2 acted as an inorganic support phase for the swellable, organic capping groups of the NPs, and the CB imparted electrical conductivity to the film. Such sensor composite films exhibited a reproducible, reversible change in relative differential resistance upon exposure to a series of organic test vapors. The response of such chemiresistive composites was comparable to, but generally somewhat smaller than, that of thiol-capped Au NPs. For a given analyte, the resistance response and signal-to-noise ratio of the capped TiO_2-NP/CB composites varied with the identity of the capping ligand. Hence, an array of TiO_2-NP/CB composites, with each film having a compositionally different carboxylate capping ligand, provided good vapor discrimination and quantification when exposed to a series of organic vapors. Principal components analysis of the relative differential resistance response of the sensor array revealed a clear clustering of the response for each analyte tested. This approach expands the options for composite-based chemiresistive vapor sensing, from use of organic monomeric or polymeric sorbent phases, to use of electrically insulating capped inorganic NPs as the nonconductive phase of chemiresistive composite vapor sensors.
|Additional Information:||© 2011 Elsevier B.V. Received 11 November 2010; Accepted 6 April 2011. Available online 14 April 2011. The authors thank Dr. Marc D. Woodka for helpful discussions and data analysis, Heather Agnew for helping with the FTIR analysis, Carol M. Garland for the TEM analysis and Juan S. Ramirez for the centrifugation of the nanoparticles. Edgardo García-Berríos acknowledges the NSF for a graduate fellowship. Ting Gao acknowledges the support from Tyco Electronics. Research was carried out in the Molecular Materials Research Center of the Beckman Institute at Caltech. This work was supported by the NSF, grant CHE-0604894, and by DHS, grant HSARPA 2008-ST-061-ED0002.|
|Subject Keywords:||Titanium (IV) dioxide nanoparticles; Carbon black composites; Electronic nose; Principal components analysis (PCA)|
|Official Citation:||Edgardo García-Berríos, Ting Gao, Don Walker, Bruce S. Brunschwig, Nathan S. Lewis, Composites of carboxylate-capped TiO2 nanoparticles and carbon black as chemiresistive vapor sensors, Sensors and Actuators B: Chemical, Volume 158, Issue 1, 15 November 2011, Pages 17-22, ISSN 0925-4005, 10.1016/j.snb.2011.04.022. (http://www.sciencedirect.com/science/article/pii/S0925400511003017)|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||08 Nov 2011 22:07|
|Last Modified:||08 Nov 2011 22:07|
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