Nanocarbon based ionic actuators—a review

Abstract

Nanocarbons represented especially by carbon nanotubes (CNTs) and graphene have been of great interest during the last two decades, both from a fundamental point of view and for future applications. The most eye-catching features of carbon nanostructures (CNSs) are their electronic, mechanical, optical and chemical characteristics, which open a way for versatile applications. Among those future prospects, actuators are one of the promising technologies. Since 1999 when the first macroscopic actuator containing CNTs was reported, the interest of utilizing these materials as well as other CNSs in active systems has been triggered all over the world. This paper gives a thorough review as well as in-depth descriptions of the many aspects of nanocarbon-based actuators. The review covers aspects of worldwide research and development of nanocarbon ionic actuators up to 2012. Materials which are covered by this review include CNTs and their composites, carbon nanofibres (CNFs), graphene and its derivatives, microporous carbon materials (for example carbide derived carbons (CDCs) and carbon aerogels) as well as the possible combinations of these materials. The considered aspects cover the following fields: synthesis and characterization of the investigated materials, the actuation mechanism as well as modelling and simulation. Applications comprising system integration and device development are also reviewed within this paper.

Novel actuators based on polypyrrole/carbide-derived carbon hybrid materials

“…PPy(DBS)CDC showed 1.17% volume change per 1 mC inserted charge compared to 0.6% per mC of PPy(DBS). This improvement is very important since the low energy efficiency is a major drawback for ionic EAPs [41]. The PPy(DBS)CDC hybrid material showed a slightly increased oxidative synthesis potential ( Figure 3) as well as slightly reduced redox currents ( Figure 6).…”

Electrochemical actuation of multiwall carbon nanotube fiber with embedded carbide-derived carbon particles

“…Nanocarbon based materials such as the multiwall carbon nanotube (MWCNT) and the carbide-derived carbon (CDC) exhibit remarkable physical and chemical properties [1]. Micro and nano fibers of SWCNT (single wall carbon nanotubes) and MWCNT have exceptional physical properties: a tensile strength of 3.3 GPa and a Young's modulus of 263 GPa [2,3] (for comparison, the tensile strength of high-tensile-strength steel is 2-2.5 GPa and Young's modulus ~200 GPa) [4]).…”

Stimulus-active polymer actuators for next-generation microfluidic devices

“…Cantilever-like actuators have typically been realized either in direct contact with a c SEM of loose, expanded microspheres (average diameter of 17.8 ± 3.8 lm). From [49], Ó2013 IOP Publishing Ltd. Reproduced with permission liquid electrolyte or as a multilayer structure with organic electrolytes, and reviews of such concepts are given in [56,57]. Another interesting application in microfluidics was described in [58], where conductive composites and fluids with giant electrorheological properties were combined to realize a microfluidic logic switch and inverter in a single microfluidic chip.…”

“…Bucky gel actuators (BGAs) have electrodes that are composed of carbon nanotubes (CNTs), and the porous structure in between is made of an electrically insulating but ion-permeable polymer membrane that contains an ionic liquid [57]. The exact working mechanisms are still disputed, but roughly speaking the electric-field-induced transport of ions and the associated dimensional change in the carbon particles leads to asymmetrically distributed stresses and thus deformations of the laminate structures.…”