Open AccessThe nonlinear sensing property and electric mechanism of carbon humidity-sensitive membranes
Author(s) -
Huan Chen,
Peng Zhen-Kang,
Gang Fu
Publication year - 2009
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.58.7904
Subject(s) - materials science , membrane , humidity , carbon black , carbon fibers , scanning electron microscope , voltage , electrical resistance and conductance , dielectric spectroscopy , composite material , electrode , analytical chemistry (journal) , chemical engineering , electrical engineering , chemistry , electrochemistry , physics , thermodynamics , organic chemistry , biochemistry , natural rubber , composite number , engineering
The nonlinear sensing property and electric mechanism of carbon humidity-sensitive membranes under investigation were manufactured by using hydroxyethyl cellulose HEC, carbon black CB and humidizer sorbitol. Microstructures examined by scanning electronic microscopy SEM show that, an effective carbon black electric network in humidity-sensing membrane would make the membrane’s resistance to have strong nonlinear property near 80%RH; so that the amount of 2wt% carbon black is in the proximity of the electric percolation threshold. The voltage-current characteristic suggested that the nonlinear sensing property and electric mechanism of the carbon humidity membranes are closely related. Particularly, impedance spectroscopy of sample at 92%RH was made up by two semi-circular arcs and a straight tail near 45° angle. The membrane′s equivalent circuit was three RC circuits in series that corresponds to the contributions of the carbon bulk resistance, CB-grain-boundary resistance and electrode contact resistance, respectively.