High performance electrochemical and electrothermal artificial muscles from twist-spun carbon nanotube yarn

Lee Jae Ah,Baughman Ray H,Kim Seon Jeong 나노기술연구협의회 2015 Nano Convergence Vol.2 No.8

High performance torsional and tensile artificial muscles are described, which utilize thermally- or electrochemically-induced volume changes of twist-spun, guest-filled, carbon nanotube (CNT) yarns. These yarns were prepared by incorporating twist in carbon nanotube sheets drawn from spinnable CNT forests. Inserting high twist into the CNT yarn results in yarn coiling, which can dramatically amplify tensile stroke and work capabilities compared with that for the non-coiled twisted yarn. When electrochemically driven in a liquid electrolyte, these artificial muscles can generate a torsional rotation per muscle length that is over 1000 times higher than for previously reported torsional muscles. All-solid-state torsional electrochemical yarn muscles have provided a large torsional muscle stroke (53° per mm of yarn length) and a tensile stroke of up to 1.3% when lifting loads that are ~25 times heavier than can be lifted by the same diameter human skeletal muscle. Over a million torsional and tensile actuation cycles have been demonstrated for thermally powered CNT hybrid yarns muscles filled with paraffin wax, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. At lower actuation rates, these thermally powered muscles provide tensile strokes of over 10%.

Electrochemical graphene/carbon nanotube yarn artificial muscles

Hyeon, Jae Sang,Park, Jong Woo,Baughman, Ray H.,Kim, Seon Jeong Elsevier 2019 Sensors and actuators. B, Chemical Vol.286 No.-

<P><B>Abstract</B></P> <P>Fiber-type artificial muscles similar to natural muscles are being studied for applications such as robots, prosthetics and exoskeletons. In particular, carbon nanotube (CNT) yarn artificial muscles have attracted interest for their unique mechanical and electrical properties as electrochemical artificial muscles. Here, we demonstrate the large tensile stroke of CNT-based electrochemical yarn artificial muscles induced by increasing capacitance. The coiled graphene/CNT yarns made by the biscrolling method can produce greater tensile actuation using more ions at the same voltage than pristine CNT coils. The maximum tensile actuation of these electrochemical muscles is 19%, which is two times larger than coiled CNT muscles with a work capacity of 2.6 J g<SUP>−1</SUP>. These electrochemical artificial muscles could be further developed for practical applications, such as micromechanical devices and robotics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Coiled graphene/CNT yarns were prepared for electrochemical artificial muscles. </LI> <LI> More ions were induced in the CNT yarns by grahpene at the same voltage. </LI> <LI> The graphene/CNT muscles contracted twice more than pristine CNT muscles through capacitance increase. </LI> </UL> </P>

Ultraviolet-induced irreversible tensile actuation of diacetylene/nylon microfibers

Chun, Kyoung-Yong,Choi, Changsoon,Baughman, Ray H,Kim, Seon Jeong IOP 2016 Smart materials & structures Vol.25 No.7

<P>Photomechanically irreversible tensile-actuated diacetylene-embedding nylon 6/6 microfibers were investigated. 10,12-pentacosadiynoic acid (PCDA) monomer, which have conventionally provided a visual color change by temperature and photo-driven stimuli, was embedded in nylon 6/6 microfibers by wet spinning. By ultraviolet (UV) (254 nm) exposure, we observed irreversible tensile actuation (contraction) of linear (untwisted) and helical (twisted) structural microfibers. The tensile contraction of twisted nylon 6/6-PCDA microfiber containing10 mM PCDA was reached to ∼2% at 60 °C. Such irreversible tensile contraction can be promoted by volume contraction of PCDA monomers during UV exposure along with irregular structural deformation containing gauche conformation with increasing temperature. The kinetics of tensile contraction with temperature and time were shown by the Arrhenius plots. The activation energies were 34.3–35.7 kJ mol<SUP>−1</SUP> as increasing the concentration of PCDA, implies that the nylon 6/6-PCDA microfibers could be applied to show time-temperature integrated device.</P>

Biothermal sensing of a torsional artificial muscle

Lee, Sung-Ho,Kim, Tae Hyeob,Lima, Má,rcio D.,Baughman, Ray H.,Kim, Seon Jeong The Royal Society of Chemistry 2016 Nanoscale Vol.8 No.6

<P>Biomolecule responsive materials have been studied intensively for use in biomedical applications as smart systems because of their unique property of responding to specific biomolecules under mild conditions. However, these materials have some challenging drawbacks that limit further practical application, including their speed of response and mechanical properties, because most are based on hydrogels. Here, we present a fast, mechanically robust biscrolled twist-spun carbon nanotube yarn as a torsional artificial muscle through entrapping an enzyme linked to a thermally sensitive hydrogel, poly(N-isopropylacrylamide), utilizing the exothermic catalytic reaction of the enzyme. The induced rotation reached an equilibrated angle in less than 2 min under mild temperature conditions (25-37 degrees C) while maintaining the mechanical properties originating from the carbon nanotubes. This biothermal sensing of a torsional artificial muscle offers a versatile platform for the recognition of various types of biomolecules by replacing the enzyme, because an exothermic reaction is a general property accompanying a biochemical transformation.</P>

Enhancement of electromagnetic interference shielding effectiveness with alignment of spinnable multiwalled carbon nanotubes

Lee, Duck Weon,Park, Jongwoo,Kim, Bum Joon,Kim, Hyunsoo,Choi, Changsoon,Baughman, Ray H.,Kim, Seon Jeong,Kim, Youn Tae Elsevier 2019 Carbon Vol.142 No.-

<P><B>Abstract</B></P> <P>This research develops a unique material to attenuate electromagnetic interference (EMI) by using spinnable multiwalled carbon nanotubes (MWNTs) combined with bio-polydimethylsiloxane (PDMS) that contains BaTiO<SUB>3</SUB> (MBPBT). In particular, a plaid pattern, formed by the spinnable MWNTs, is very effective in attenuating the propagation of EM waves,which achieves over 20 dB at 8.2–12.4 GHz (X-band frequency range). This means that a filter type of the spinnable MWNTs is actively able to handle the directionality and movement of EMI propagation. In addition, the MBPBT is characterized by its strong mechanical advantage (bending radius 180°).</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Microscopically Buckled and Macroscopically Coiled Fibers for Ultra-Stretchable Supercapacitors

Choi, Changsoon,Kim, Ji Hwan,Sim, Hyun Jun,Di, Jiangtao,Baughman, Ray H.,Kim, Seon Jeong Wiley Blackwell (John Wiley Sons) 2017 Advanced energy materials Vol.7 No.6

Alternative Nanostructures for Thermophones

Aliev, Ali E.,Mayo, Nathanael K.,Jung de Andrade, Monica,Robles, Raquel O.,Fang, Shaoli,Baughman, Ray H.,Zhang, Mei,Chen, Yongsheng,Lee, Jae Ah,Kim, Seon Jeong American Chemical Society 2015 ACS NANO Vol.9 No.5

<P>Thermophones are highly promising for applications such as high-power SONAR arrays, flexible loudspeakers, and noise cancellation devices. So far, freestanding carbon nanotube aerogel sheets provide the most attractive performance as a thermoacoustic heat source. However, the limited accessibility of large-size freestanding carbon nanotube aerogel sheets and other even more exotic materials recently investigated hampers the field. We describe alternative materials for a thermoacoustic heat source with high-energy conversion efficiency, additional functionalities, environmentally friendly, and cost-effective production technologies. We discuss the thermoacoustic performance of alternative nanostructured materials and compare their spectral and power dependencies of sound pressure in air. We demonstrate that the heat capacity of aerogel-like nanostructures can be extracted by a thorough analysis of the sound pressure spectra. The study presented here focuses on engineering thermal gradients in the vicinity of nanostructures and subsequent heat dissipation processes from the interior of encapsulated thermoacoustic projectors. Applications of thermoacoustic projectors for high-power SONAR arrays, sound cancellation, and optimal thermal design, regarding enhanced energy conversion efficiency, are discussed.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-5/nn507117a/production/images/medium/nn-2014-07117a_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn507117a'>ACS Electronic Supporting Info</A></P>

Free-standing nanocomposites with high conductivity and extensibility

Chun, Kyoung-Yong,Kim, Shi Hyeong,Shin, Min Kyoon,Kim, Youn Tae,Spinks, Geoffrey M,Aliev, Ali E,Baughman, Ray H,Kim, Seon Jeong IOP Pub 2013 Nanotechnology Vol.24 No.16

<P>The prospect of electronic circuits that are stretchable and bendable promises tantalizing applications such as skin-like electronics, roll-up displays, conformable sensors and actuators, and lightweight solar cells. The preparation of highly conductive and highly extensible materials remains a challenge for mass production applications, such as free-standing films or printable composite inks. Here we present a nanocomposite material consisting of carbon nanotubes, ionic liquid, silver nanoparticles, and polystyrene–polyisoprene–polystyrene having a high electrical conductivity of 3700 S cm<SUP>−1</SUP> that can be stretched to 288% without permanent damage. The material is prepared as a concentrated dispersion suitable for simple processing into free-standing films. For the unstrained state, the measured thermal conductivity for the electronically conducting elastomeric nanoparticle film is relatively high and shows a non-metallic temperature dependence consistent with phonon transport, while the temperature dependence of electrical resistivity is metallic. We connect an electric fan to a DC power supply using the films to demonstrate their utility as an elastomeric electronic interconnect. The huge strain sensitivity and the very low temperature coefficient of resistivity suggest their applicability as strain sensors, including those that operate directly to control motors and other devices.</P>

Elastomeric Conductive Composites Based on Carbon Nanotube Forests

Shin, Min Kyoon,Oh, Jiyoung,Lima, Marcio,Kozlov, Mikhail E.,Kim, Seon Jeong,Baughman, Ray H. WILEY-VCH Verlag 2010 Advanced Materials Vol.22 No.24

<B>Graphic Abstract</B> <P>Highly elastic and electrically conductive composite sheets are prepared by infiltration of MWNT forests with polyurethane binder. After initial pretreatment, the composite provides highly reproducible changes in resistivity at elongations up to 40%. Almost no degradation in electrical properties and a linear dependence of resistivity on strain is observed for strains in 10%–20% range. <img src='wiley_img_2010/09359648-2010-22-24-ADMA200904270-content.gif' alt='wiley_img_2010/09359648-2010-22-24-ADMA200904270-content'> </P>

Torsional behaviors of polymer-infiltrated carbon nanotube yarn muscles studied with atomic force microscopy.

Kwon, Cheong Hoon,Chun, Kyoung-Yong,Kim, Shi Hyeong,Lee, Jae-Hyeok,Kim, Jae-Ho,Lima, M?rcio D,Baughman, Ray H,Kim, Seon Jeong RSC Pub 2015 Nanoscale Vol.7 No.6

<P>Torsional behaviors of polymer-infiltrated carbon nanotube (CNT) yarn muscles have been investigated in relation to molecular architecture by using atomic force microscopy (AFM). Two polymers with different stiffnesses, polystyrene (PS) and poly(styrene-b-isoprene-b-styrene) (SIS), were uniformly infiltrated into CNT yarns for electrothermal torsional actuation. The torsional behaviors of hybrid yarn muscles are completely explained by the volume change of each polymer, based on the height and full width at half maximum profiles from the AFM morphological images. The volume expansion of the PS yarn muscle (1.7 nm of vertical change and 22 nm of horizontal change) is much larger than that of the SIS yarn muscle (0.3 nm and 11 nm change in vertical and horizontal directions) at 80 C, normalized by their values at 25 C. We demonstrate that their maximum rotations are consequently 29.7 deg mm(-1) for the PS-infiltrated CNT yarn muscle (relatively larger rotation) and 14.4 deg mm(-1) for the SIS-infiltrated CNT yarn muscle (smaller rotation) at 0.75 V m(-1). These hybrid yarn muscles could be applied in resonant controllers or damping magnetoelectric sensors.</P>