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# Investigations of the key mechanism of Carbon-Nanotube Actuators and their dependencies

Geier, Sebastian and Riemenschneider, Johannes and Mahrholz, Thorsten and Wierach, Peter and Sinapius, Michael (2010) Investigations of the key mechanism of Carbon-Nanotube Actuators and their dependencies. SPIE Smart Structures/NDT, 07.03. - 11.03. 2010, San Diego, Kalifornien, USA.

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## Abstract

Future adaptable applications require electro-mechanical actuators with a high weight-related en-ergy. Among modern multi-functional materials carbon nanotubes (CNTs) have some special char-acteristics which give them the potential to solve this demand. On the one hand raw CNTs have excellent mechanical properties like their low density (1330kg/m$^3$) and very high estimated stiffness of about 1TPa. On the other hand CNTs have the ability under presence of ions, wired like a capacitor and activated by a charge injection to perform a dimension-change (length of C-C bondings). Calculations and experiments present achievable active strains of 1$\%$ at low voltage of $\pm$1V what qualifies CNT-based materials for leightweight powerful actuators. In this paper the former work done with actuators using CNT-containing mats and Nafion as solid electrolyte is evaluated by analyzing the two main-components in more detail. On the one hand the CNT-based model-material SWCNT-mats called Bucky-paper (BP) and on the other hand ion do-nating electrolytes in liquid-phase like a NaCl-solution and its solid equivalent Nafion as thin-foils are tested. Additional methods of fabrication, preparation and characterization of the CNT-powder and the manufactured BPs containing randomly oriented single-walled carbon nanotubes (SWCNTs) are presented which provide a deeper system-understanding. Both materials (BPs and Nafion-foils) are intensively investigated in different deflection-test-rigs due to their structural as-sembly. This paper presents a method for electro-mechanical measurements of BPs in an in-plain test set-up which avoids sensing secondary effects like thermal expansion or mass-transport and confirm that BP-deflection should only be a capacity-driven effect. Nafion as solid electrolyte will be tested in an out-of-plane facility to measure its possible actuation within the lamellar-direction. With this approach the dependencies of each component and their individual characters on the deflec-tion can be estimated. The active response can be referred to the internal structure of both compo-nents as well as of the whole structural assembly. The results give a certain direction to a BP-optimization referring to active strain, density, structural integrity and conductibility. In addition to these facts the active character of BPs using CNTs of different suppliers and Nafion is analyzed. These investigations are of particular importance for detection of global dependencies and using both materials in a hybrid-assembly like solid actuators which are needed for structural applications.

Document Type:Conference or Workshop Item (Speech, Paper)
Title:Investigations of the key mechanism of Carbon-Nanotube Actuators and their dependencies
Authors:
AuthorsInstitution or Email of Authors
Geier, SebastianUNSPECIFIED
Riemenschneider, JohannesUNSPECIFIED
Mahrholz, ThorstenUNSPECIFIED
Wierach, PeterUNSPECIFIED
Sinapius, MichaelUNSPECIFIED
Date:March 2010
Refereed publication:Yes
In ISI Web of Science:No
Keywords:Carbon nanotube, actuator, Bucky paper, liquid electrolyte, solid electrolyte
Event Title:SPIE Smart Structures/NDT
Event Location:San Diego, Kalifornien, USA
Event Type:international Conference
Event Dates:07.03. - 11.03. 2010
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Structures & Materials
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Multifunctional Materials
Deposited By: Doris Ries
Deposited On:16 Dec 2010 12:28