Abstract
Carbon Nanotube (CNT) agglomerates can be aligned along field lines between adjacent electrodes to form conductive bridges. This study discusses the step-wise process of dielectrophoretic deposition of CNTs to form conducting bridges between adjacent electrodes. For the first time, the creation of conductive CNT bridges spanning lengths over 50 microns is demonstrated. The CNT bridges are permanently secured using electrodeposition of the conducting polymer polypyrrole. Morphologies of the CNT bridges formed within a frequency range of 1 kHz and 10 MHz are explored and explained as a consequence of interplay between dielectrophoretic and electroosmotic forces. Postdeposition heat treatment increases the conductivity of CNT bridges, likely due to solvent evaporation and resulting surface tension inducing better contact between CNTs.
Highlights
Carbon nanotubes (CNTs), high-aspect ratio tubular carbon structures [1], have drawn considerable interest due to their extraordinary physical, mechanical, and electrical properties [2]
CNTs are often used for the enhanced performance of electronic devices such as chemical and biological sensors [3], field-effect transistors [4,5,6], energy storage systems [7], computing devices [8,9], and conductive interconnects [10,11]
A variety of techniques have been developed to assemble or manipulate individual CNTs or CNT bundles onto desired electrode locations
Summary
Carbon nanotubes (CNTs), high-aspect ratio tubular carbon structures [1], have drawn considerable interest due to their extraordinary physical, mechanical, and electrical properties [2]. We describe a step-wise process that can produce conductive bridges, selfassembled out of a CNT suspension and constructed within the high field areas between adjacent electrodes under the influence of dielectrophoresis (DEP). Dielectrophoresis refers to the force exerted by an external electric field on the induced dipole moment of a particle (i.e., a nanotube) suspended in a dielectric medium [22]. Under an applied AC field, these complex permittivities vary throughout a range of frequencies, and determine the direction and magnitude of the DEP force. If the real part of the complex permittivity of the particle is greater than that of the fluid medium, the DEP force will be “positive” or directed towards the point of the highest field’s intensity. In order to achieve this result, we employ the technique of step-wise DEP deposition described below
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