CVD-grown multi-walled carbon nanotubes (CNTs) in suspension were aligned and collected by an AC electric field developed within an inter-digitated electrode structure. The increases of conductance and capacitance were observed and monitored by dielectric spectroscopy and attributed to the accumulations of CNTs. Comparisons of the capacitance and conductance changes of aligned CNTs in different solvents were made. Among these, CNTs in distilled water showed the greatest increases in both conductance and capacitance. As the field is switched on or off, the conductance and capacitance of the CNTs show substantial reversible changes superimposed on the underlying increasing trend. (C) 2003 Elsevier B.V. All rights reserved.