A vapor response mechanism study of surface-modified single-walled carbon nanotubes coated chemiresistors and quartz crystal microbalance sensor arrays

Hung Ling Lu, Chia Jung Lu, Wei Cheng Tian, Horn Jiunn Sheen

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

This paper compares the selectivity and discusses the response mechanisms of various surface-modified, single-walled carbon nanotube (SWCNT)-coated sensor arrays for the detection of volatile organic compounds (VOCs). Two types of sensor platforms, chemiresistor and quartz crystal microbalance (QCM), were used to probe the resistance changes and absorption masses during vapor sensing. Four sensing materials were used in this comparison study: pristine, acidified, esterified, and surfactant (sodium dodecyl sulfate, SDS)-coated SWCNTs. SWCNT-coated QCMs reached the response equilibrium faster than the chemiresistors did, which revealed a delay diffusion behavior at the inter-tube junction. In addition, the calibration lines for QCMs were all linear, but the chemiresistors showed curvature calibration lines which indicated less effectiveness of swelling at high concentrations. While the sorption of vapor molecules caused an increase in the resistance for most SWCNTs due to the swelling, the acidified SWCNTs showed no responses to nonpolar vapors and a negative response to hydrogen bond acceptors. This discovery provided insight into the inter-tube interlocks and conductivity modulation of acidified SWCNTs via a hydrogen bond. The results in this study provide a stepping-stone for further understanding of the mechanisms behind the vapor selectivity of surface-modified SWCNT sensor arrays.

Original languageEnglish
Pages (from-to)467-474
Number of pages8
JournalTalanta
Volume131
DOIs
Publication statusPublished - 2015 Jan

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Keywords

  • Carbon nano-tubes
  • Chemiresistor
  • Gas sensor
  • Quartz crystal microbalance
  • Volatile organic compounds

ASJC Scopus subject areas

  • Analytical Chemistry

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