Electric field-modulated non-ohmic behavior of carbon nanotube fibers in polar liquids.

We report a previously unseen non-ohmic effect in which the resistivity of carbon nanotube fibers immersed in polar liquids is modulated by the applied electric field. This behavior depends on the surface energy, dielectric constant, and viscosity of the immersion media. Supported by synchrotron SAXS and impedance spectroscopy, we propose a model in which the gap distance, and thus the conductance, of capacitive interbundle junctions is controlled by the applied field.JT acknowledges generous financial support from: The Cambridge Commonwealth European and International Trust, CONACyT (Mexico), Dyson Ltd, and Pembroke College Cambridge. JJV acknowledges support from MINECO (Spain) and FP7-People-Marie Curie Action-CIG.This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/nn5030835

Additive functionalization and embroidery for manufacturing wearable and washable textile supercapacitors

202307 bcwhAccepted ManuscriptRGCPublishe

Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles

CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOSuperelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short-and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short-and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.3496246400404CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES [12264/13-0]FAPESP [2013/08293-7]12264/13-02013/08293-7We thank A. Ruhparwar, S. F. Cogan, and X. Li for discussions of pacemaker applicationsX. Zhang, B. Lin, X. Zhou, Y. Hou, and F. Jia for sample preparationsH. Luo for mechanical properties characterizationsA. Needleman for discussions on periodic necking and bucklingT. Xu, L. Tong, H. Zhang, and Y. Du for discussions on modeling and measurement techniquesand D. Wang for drawings. Support in the United States was from Air Force Office of Scientific Research grants FA9550-12-1-0211, FA9550-15-1-0089, and FA9550-14-1-0227Robert A. Welch Foundation grant AT-0029U.S. Army grants W91CRB-14-C-0019 and W91CRB-13-C-0037Department of Defense grant W81XWH-14-1-0228NIH grant 1R01DC011585-01NSF grants CMMI-1031829, CMMI-1120382, CMMI-1335204, and ECCS-1307997Office of Naval Research Multidisciplinary University Research Initiative grant NOOD14-11-1-0691and the Louis A. Beecherl Jr. Chair. Support in China was from the Priority Academic Program Development of Jiangsu Higher Education Institutions on Renewable Energy Materials Science and Engineering, Jiangsu Key Laboratory for Photovoltaic Engineering Science, Jiangsu Specially-Appointed Professor Program Sujiaoshi-2012-34, National Natural Science Foundation of China grant 31200637, Jiangsu Basic Research Program grant BK2012148, Science and Technology Support Program of Changzhou grants CC20140016 and CZ20140013, Chinese Ministry of Science and Technology grant 2013AA014201, and State Scholarship Fund grant 201406290125. Brazilian support was from Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Scholarship 12264/13-0 and Fundação de Amparo à Pesquisa do Estado de São Paulo-Centros de Pesquisa, Inovação e Difusão grant 2013/08293-7. A provisional patent application has been filed

Hydroxyl-functionalized and N-doped multiwalled carbon nanotubes decorated with silver nanoparticles preserve cellular function

The present study aims to investigate biocompatibility of silver nanoparticles (Ag-NPs) anchored to different types of multiwalled carbon nanotubes (MWNTs). The MWNTs were decorated with Ag-NPs via a novel chemical route without using any sulfur containing reagent. Three different MWNTs were used as substrate materials for anchoring Ag-NPs: MWNTs-Ag (pure carbon), COx-MWNTs-Ag (carboxyl functionalized), and CNx-MWNTs-Ag (nitrogen-doped). The Ag-NPs, synthesized without thiol capping groups, and which were strongly anchored to the nanotubes surfaces, exhibit an average size of 7 ± 1, 10 ± 1, and 12 ± 1 nm in MWNTs, COx-MWNTs, and CNx-MWNTs, respectively. To determine biocompatibility of these three types of novel hybrid Ag-nanotube materials, cellular function and immune response were evaluated in the human keratinocyte cell line (HaCaT). Cellular assays revealed marginal toxicity after 24 h, and full cellular recovery was observed at 48 h based on an MTS assay for cellular viability. Therefore, Ag-nanotube systems appear to be very different from isolated dispersed Ag-NPs, and due to the strong interactions between the Ag-NPs and the doped nanotube surfaces, they make the Ag particles less toxic because they are not released easily to the cells. Pure carbon MWNTs appear to start releasing Ag-NPs at periods longer than 1 week by an observed decrease in cell proliferation. However, the use of N- and COx-doped MWNTs do not appear to release Ag-NPs to the cells due to the strong binding to the tube surfaces caused by the doped sites. We envisage the use of COx-MWNTs, and CNx-MWNTs anchored with Ag-NP as efficient drug delivery carriers and biosensors. © 2011 American Chemical Society

Focused ion beam milling of carbon nanotube yarns and bucky-papers : correlating their internal structure with their macro-properties

Focused ion beam (FIB) milling through carbon nanotube (CNT) yarns and bucky-papers followed by scanning electron microscopy has recently emerged as a powerful tool for eliciting details of their internal structure. The internal arrangement of CNTs in bucky-papers and yarns directly affects their performance and characteristics. Consequently this information is critical for further optimisation of these structures and to tailor their properties for specific applications. This chapter describes in detail FIB milling of CNT yarns and bucky-papers and gives a range of examples where FIB milling has enabled a better understanding of how processing conditions and treatments affect the internal structure. Emphasis is placed on how FIB milling elucidates the influence of fabrication conditions on the internal arrangement of CNTs and how this influences the material\u27s macroscopic properties