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Improved Chemical Detection and Ultra-Fast Recovery Using Oxygen Functionalized Epitaxial Graphene Sensors

Lookup NU author(s): Dr Venkata Nagareddy, HK Chan, Professor Jon Goss, Professor Nick Wright, Dr Kurt Gaskill, Dr Alton Horsfall

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Abstract

Oxygen functionalized epitaxial graphene (OFEG) sensors are demonstrated toward the sensing of polar chemical vapors at room temperature. The electrical characteristics of the sensor show an increase in resistance upon exposure to polar protic chemicals while the resistance decreased for polar aprotic vapors The average response and recovery times of the OFEG sensor to all analyte vapors are 10 and 100 s, respectively. In comparison, non-functionalized epitaxial graphene (NFEG) sensors show similar response times as OFEG, but with extremely long recovery rates in the range of similar to 1.5-2 hours. The dipole moment of the chemical is found to have a strong impact on the magnitude of the response for both OFEG and NFEG which increased with the increasing dipole moment from 2.0 D to 4.1 D. However, OFEG exhibits significantly higher sensitivity (twofold increase) to all polar chemicals over NFEG sensors. For example, exposing OFEG to n-methyl-2-pyrrolidone vapors produces a 45% change in resistance, in comparison to a 27% resistance change displayed by NFEG sensors. The noise spectral density of NFEG follows a typical 1/f dependence upon exposure to di-methylformamide vapors but with a lower change in noise from 1 x 10(-18)A(2)/Hz to 1 x 10(-17) A(2)/Hz at 1 Hz. In contrast, OFEG displays a unique 1/f(2) behavior at lower frequency range (1-10 Hz) with a significant change to the sensor noise from 3 x 10(-18)A(2)/Hz to 2 x 10(-15) A(2)/Hz.

Publication metadata

Author(s): Nagareddy VK, Chan HK, Hernandez SC, Wheeler VD, Nyakiti LO, Myers-Ward RL, Eddy CR, Goss JP, Wright NG, Walton SG, Gaskill DK, Horsfall AB

Publication type: Article

Publication status: Published

Journal: IEEE Sensors Journal

Year: 2013

Volume: 13

Issue: 8

Pages: 2810-2817

Print publication date: 01/08/2013

Online publication date: 19/04/2013

Acceptance date: 03/04/2013

ISSN (print): 1530-437X

ISSN (electronic): 1558-1748

Publisher: IEEE

URL: http://dx.doi.org/10.1109/JSEN.2013.2259154

DOI: 10.1109/JSEN.2013.2259154

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