title: Highly sensitive optical detection of humidity on polymer/metal nanoparticle hybrid films.
abstract: Porous metal films for optical humidity sensing were prepared from copper nanoparticles protected by a 2-3 nm carbon coating, a silicon tenside, and a polymeric wetting agent. Exposure to water or solvent vapor revealed an exceptional sensitivity with optical shifts in the visible light range of up to 50 nm for a change of 1% in relative humidity. These properties could be attributed to a combination of surface plasmon resonance effects at low humidity and thin film interference at higher water or solvent concentration in the surrounding air. The simple concept and use of ultra-low-cost materials suggests application of such porous metal-film-based optical humidity sensors in large-scale applications for food handling, storage, and transport.
authors.affiliation: Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Norman A
authors.initials: NA
authors.lastname: Luechinger
authors.forename: Stefan
authors.initials: S
authors.lastname: Loher
authors.forename: Evagelos K
authors.initials: EK
authors.lastname: Athanassiou
authors.forename: Robert N
authors.initials: RN
authors.lastname: Grass
authors.forename: Wendelin J
authors.initials: WJ
authors.lastname: Stark
mesh_terms: D000388:Air; D002244:Carbon / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D003300:Copper / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D006813:Humidity; D053768:Metal Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D011312:Pressure; D012997:Solvents / Q000737:chemistry; D020349:Surface Plasmon Resonance; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D011108:Polymers; D012997:Solvents; D014867:Water; D002244:Carbon; D003300:Copper