Chemical sensors using coated or doped carbon nanotube networks

US7801687B1 · kind B1 · utility

Assignee

• The United States of America as Represented by the Administrator of the National Aeronautics and Space Administration (NASA) · US

Inventors

• Jing Li · Houston, US
• Meyya Meyyappan · San Jose, US

Key dates

• Filing date: Jul 8, 2005
• Grant date: Sep 21, 2010
• Expiry date: Feb 1, 2028

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S977/938
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Methods for using modified single wall carbon nanotubes (“SWCNTs”) to detect presence and/or concentration of a gas component, such as a halogen (e.g., Cl2), hydrogen halides (e.g., HCl), a hydrocarbon (e.g., CnH2n+2), an alcohol, an aldehyde or a ketone, to which an unmodified SWCNT is substantially non-reactive. In a first embodiment, a connected network of SWCNTs is coated with a selected polymer, such as chlorosulfonated polyethylene, hydroxypropyl cellulose, polystyrene and/or polyvinylalcohol, and change in an electrical parameter or response value (e.g., conductance, current, voltage difference or resistance) of the coated versus uncoated SWCNT networks is analyzed. In a second embodiment, the network is doped with a transition element, such as Pd, Pt, Rh, Ir, Ru, Os and/or Au, and change in an electrical parameter value is again analyzed. The parameter change value depends monotonically, not necessarily linearly, upon concentration of the gas component. Two general algorithms are presented for estimating concentration value(s), or upper or lower concentration bounds on such values, from measured differences of response values.