A Carbon Nanotube-based Sensor for CO2 Monitoring

A carbon dioxide (CO2) sensor is fabricated by depositing a thin layer of a multiwall carbon nanotube (MWNT) – silicon dioxide (SiO2) composite upon a planar inductorcapacitor resonant circuit. By tracking the resonant frequency of the sensor the complex permittivity of the coating material can be determined. It is shown that the permittivity of MWNTs changes linearly in response to CO2 concentration, enabling monitoring of ambient CO2 levels. The passive sensor is remotely monitored with a loop antenna, enabling measurements from within opaque, sealed containers. Experimental results show the response of the sensor is linear, reversible with no hysteresis between increasing and decreasing CO2 concentrations, and with a response time of approximately 45 s. An array of three such sensors, comprised of an uncoated, SiO2 coated, and a MWNT-SiO2 coated sensors is used to self-calibrate the measurement for operation in a variable humidity and temperature environment. Using the sensor array CO2 levels can be measured in a variable humidity and temperature environment to a ± 3% accuracy.

[1]  Tatsumi Ishihara,et al.  A practical capacitive type CO2 sensor using CeO2/BaCO3/CuO ceramics , 2000 .

[2]  H. Dai,et al.  Individual single-wall carbon nanotubes as quantum wires , 1997, Nature.

[3]  S. Ramo,et al.  Fields and Waves in Communication Electronics , 1966 .

[4]  Min-Suk Lee,et al.  A new process for fabricating CO2-sensing layers based on BaTiO3 and additives , 2000 .

[5]  Kong,et al.  Nanotube molecular wires as chemical sensors , 2000, Science.

[6]  Zettl,et al.  Extreme oxygen sensitivity of electronic properties of carbon nanotubes , 2000, Science.

[7]  P. Dalgaard,et al.  Application of an iterative approach for development of a microbial model predicting the shelf-life of packed fish. , 1997, International journal of food microbiology.

[8]  W. D. de Heer,et al.  A Carbon Nanotube Field-Emission Electron Source , 1995, Science.

[9]  Charles M. Lieber,et al.  Carbon nanotube-based nonvolatile random access memory for molecular computing , 2000, Science.

[10]  Christopher L. Davey,et al.  The dielectric properties of biological cells at radiofrequencies : Applications in biotechnology , 1999 .

[11]  T Lindgren,et al.  Cabin environment and perception of cabin air quality among commercial aircrew. , 2000, Aviation, space, and environmental medicine.

[12]  Herbert Shea,et al.  Single- and multi-wall carbon nanotube field-effect transistors , 1998 .

[13]  C. Marliere,et al.  EFFECT OF GAS ADSORPTION ON THE ELECTRICAL PROPERTIES OF SINGLE WALLED CARBON NANOTUBES MATS , 1999 .

[14]  Patrick Bernier,et al.  Carbon nanotubes and gas adsorption , 1999 .

[15]  Hanns-Erik Endres,et al.  A capacitive CO2 sensor system with suppression of the humidity interference , 1999 .

[16]  Peter Zeppenfeld,et al.  Methane mobility in carbon nanotubes , 2000 .

[17]  S. Drost,et al.  Optimization of the geometry of gas-sensitive interdigital capacitors , 1991 .

[18]  J. DeSimone,et al.  CO2 Technology Platform: An Important Tool for Environmental Problem Solving. , 2001, Angewandte Chemie.

[19]  S. Tans,et al.  Room-temperature transistor based on a single carbon nanotube , 1998, Nature.

[20]  Norman F. Sheppard,et al.  Design of a conductimetric pH microsensor based on reversibly swelling hydrogels , 1993 .

[21]  A. Rinzler,et al.  Carbon nanotube actuators , 1999, Science.

[22]  John F. Currie,et al.  Micromachined thin film solid state electrochemical CO2, NO2 and SO2 gas sensors , 1999 .

[23]  Eklund,et al.  Effects of gas adsorption and collisions on electrical transport in single-walled carbon nanotubes , 2000, Physical review letters.

[24]  Zhen Yao,et al.  Carbon nanotube intramolecular junctions , 1999, Nature.

[25]  A. Rao,et al.  Continuous production of aligned carbon nanotubes: a step closer to commercial realization , 1999 .

[26]  K. G. Ong,et al.  A resonant printed-circuit sensor for remote query monitoring of environmental parameters , 2000 .