Electromechanical actuation of macroscopic carbon nanotube structures: mats and aligned ribbons

Suppiger, D.; Busato, Stephan; Ermanni, Paolo; Motta, Marcelo; Windle, Alan H.

doi:10.1039/b822862k

Cited by 17 publications

(15 citation statements)

References 15 publications

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“…However, a strong inverse correlation of Young's modulus and free strain is reported. 10 Fig. 1 represents similar results with respect of mechanical properties linked to different manufacturing strategies.…”

Section: Introductionsupporting

confidence: 78%

Actuation-mechanisms of CNT-bucky papers and CNT-arrays

et al. 2015

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In the fields of smart materials there is still a demand for a material featuring high modulus, low density and large strain. Carbon materials catch enormous scientific attention not only since carbon fibers were used for highperformance composite structures. But more and more the scientific attention moves from the macroscale to the nanoscale. This paper focuses with a adaptive point of view on one of the carbon allotropes: carbon nanotubes (CNTs). Beside excellent electromechanical properties another interesting feature was first mentioned 1999 -the active behavior of paper-like mats (bucky-papers) made of CNTs. CNT-papers are electrically activated using a double-layer interaction of ions provided by an electrolyte and the charged, high specific surface area of the paper formed by carbon nanotubes. Until now the detailed mechanism behind the strain/force generation of CNT-based architectures is unknown. A clarification of this principle reveals the potential of carbon tubes to be or not to be a resilient smart material in order to use their strong covalent carbon bonds instead of weak van der Waals force as tube-linking. This paper presents further investigations about the composition of CNT-papers and their performance in contrast to vertical aligned CNT-arrays using an actuated tensile test set-up. For better comparison the experiments of both specimen-types are carried out in dry, wet and wet/charged conditions. Especially in the case of CNT-arrays it is essential to preload the specimens because the curly CNT-structure superimposes the vertical orientation. While the CNT-paper is tested in an aqueous solution of one molar sodium chloride, the hydrophobic character of CNT-arrays requires an ionic liquid (IL) as electrolyte. It is found that the mechanical properties of CNT-papers drop significantly by wetting and can be controlled by charging what indicates an electrostatic dominated effect. In contrast the CNT-arrays show identical results regardless of the test conditions and furthermore an active, reversible behavior of tube elongation by charging. These results indicate strongly a quantum mechanical effect as reason of a CNT-array actuation.

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Section: Introductionsupporting

confidence: 78%

Actuation-mechanisms of CNT-bucky papers and CNT-arrays

et al. 2015

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“…Just a few examples of proposed graphene applications include nano-electronics, 2 biosensing, 3 solar energy harvesting, 4 desalination, 5 and actuation. [6][7][8][9]12,13 In a recent article, we investigated the electromechanical response of pristine monolayer graphene both in air and upon immersion in a liquid electrolyte, 12 where it was shown that the presence of an electrostatic double-layer (EDL) is necessary to produce high strain generation in pristine graphene and carbon nanotube (CNT) based actuators. However, an inherent limitation associated with actuation via the EDL effect is the low actuation rates.…”

mentioning

confidence: 99%

Monolayer graphene oxide as a building block for artificial muscles

Rogers

Liu

2013

Applied Physics Letters

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The electromechanical actuation of a highly ordered compound of graphene oxide (GO) is shown via ab initio simulations to produce high-performance quantum-mechanical responses, which mimic the behaviour of mammalian skeletal muscle. In addition to large expansive strains (∼10%), this GO compound (asymmetrically unzipped C4O) exhibits large contractive strains of −4.8% upon −0.15 e/C-atom electron injection. Furthermore, as these contractive strains are coupled with equally high stresses (∼100 GPa) and short response times (∼1 ns), we show that this GO material meets all of the functional requirements of an artificial muscle building block.

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“…Both explanations might hold as well for the MWCNT/PPy hybrids. Additionally, the adhesion to the MWCNTs, which have a relatively high stiffness and negligible actuation strain, strongly restricts the expansion/contraction in direction parallel to the MWCNT orientation and therefore increases the relative differences of the actuation strains for the parallel (in‐plane) and perpendicular (out‐of‐plane) direction (thin polypyrrole film: out‐of‐plane/in‐plane: 18%, MWCNT/PPy perpendicular/parallel: 143%). The actuation force is transferred throughout the film thickness, perpendicular to the global MWCNT orientation by the contact points that are established during coating of the MWCNTs.…”

Section: Resultsmentioning

confidence: 99%

Nanostructured MWCNT/Polypyrrole Actuators with Anisotropic Strain Response

et al. 2015

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Conducting polymers (CP) as an active material in electrochemical actuators are often likened to "artificial muscles". To transfer the isotropic change of volume in the CP component into an anisotropic actuation as in a natural muscle, different design approaches, mostly bilayer or triple layer bending devices, have been studied. Herein, we report a novel actuator design with an almost linear strain response, consisting of nanostructured aligned multi-walled carbon nanotube arrays in which each MWCNT is individually coated with a thin layer of polypyrrole.

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Electromechanical actuation of macroscopic carbon nanotube structures: mats and aligned ribbons

Cited by 17 publications

References 15 publications

Actuation-mechanisms of CNT-bucky papers and CNT-arrays

Actuation-mechanisms of CNT-bucky papers and CNT-arrays

Monolayer graphene oxide as a building block for artificial muscles

Nanostructured MWCNT/Polypyrrole Actuators with Anisotropic Strain Response

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