PH -dependent conductance behaviors of layer-by-layer self-assembled carboxylated carbon nanotube multilayer thin-film sensors

Dongjin Lee, Tianhong Cui

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

The authors report pH -dependent conductance behaviors of single-walled carbon nanotube (SWCNT) multilayer thin-film sensors. SWCNTs are functionalized with carboxylic groups, and layer-by-layer assembled alternatively with polycation, polydiallyldimethyammonium chloride on the microfabricated metal electrodes. Current-voltage (I-V) characteristics show that the conductance of SWCNT multilayer thin-film sensors decreases with increase of pH values. On the other hand, the multilayer resistors with polymethylmethacrylate (PMMA) as a passivation layer demonstrate the increasing conductance with pH, opposite to the case of the absence of PMMA layer. The conductance change in the absence of PMMA attributes to doping/undoping of holes as charge carriers by molecular protonation/deprotonation of p -type semiconducting SWCNTs. With PMMA layer, concentration gradient of hydrogen ions on the dielectric forms the gate bias voltage, which changes the conductance of underlying semiconducting SWCNT layer. Each pH -dependent behavior has versatile applications for chemical and biological detections.

Original languageEnglish (US)
Pages (from-to)842-848
Number of pages7
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Volume27
Issue number2
DOIs
StatePublished - 2009

Bibliographical note

Funding Information:
This work was partially supported by the DARPA M/NEMS Science and Technology Fundamental Research Program through the Micro/Nano Fluidic Fundamental Focus (MF3) Center. The authors would like to thank the Nanofabrication Center and Characterization Facility at the University of Minnesota for the help with fabrication and characterization.

Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.

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