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Proceedings Paper

Carbon nanotube sheet actuator: theoretical and experimental investigations
Author(s): Mohammad H. Haque; Ivica Kolaric; Uwe Vohrer; Thomas Wallmersperger; Bernd Kroeplin
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Paper Abstract

In this paper we present experimental measurements as well as a theoretical model for the electro-mechanical behavior of single walled carbon nanotube (SWNT) sheet actuators. The SWNT material exhibits elongation and contraction of the carbon bond length due to electro-chemically induced surface charge and works at a relatively low operating voltage. The use of carbon nanotube sheet material sandwich with porous ceramic is a special feature of the presented work. In the experiment, two layers of SWNT with a ceramic layer in between were placed between two working-electrodes in an electrolyte solution bath. The counter electrode has been placed within the solution away from the composite. The charge transfer takes place between the working and the counter electrodes. The displacement of the composite was measured in the thickness direction, i.e. between the fixed and the mobile working electrodes. Depending on the applied voltage, different displacement values up to 0.8% of its original thickness were obtained. As influencing factors, the parameters such as applied electric field, thickness of the composite, solvent and electrode type were investigated. A clear dependency of the actuation on the applied potential was observed within the electro-chemical window. It is remarkable that an applied electric voltage exceeding the window leads to a hydrolysis of the solvent, i.e. generation of gas bubbles. In the theoretical part, a macroscopic model for the actuation of the SWNT material has been developed. A mechanical field equation which uses the applied electric potential as input gives the elongation and contraction of the material. Depending on the parameters given above, the time-behavior of the actuator has been simulated. Thus, by various numerical simulations and experimental investigations, the actuator-characteristic can be optimized. In conclusion, a good correlation between the experimental and the numerical results has been determined.

Paper Details

Date Published: 27 July 2004
PDF: 11 pages
Proc. SPIE 5385, Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD), (27 July 2004); doi: 10.1117/12.539496
Show Author Affiliations
Mohammad H. Haque, Fraunhofer-Technologie-Entwicklungsgruppe (Germany)
Ivica Kolaric, Fraunhofer-Technologie-Entwicklungsgruppe (Germany)
Uwe Vohrer, Fraunhofer-Institut fur Grenzflaechen- und Bioverfahrenstechnik (Germany)
Thomas Wallmersperger, Univ. Stuttgart (Germany)
Bernd Kroeplin, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 5385:
Smart Structures and Materials 2004: Electroactive Polymer Actuators and Devices (EAPAD)
Yoseph Bar-Cohen, Editor(s)

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