Actuators of individual carbon nanotubes

SiegmarRoth,RayH.Baughman 한국물리학회 2002 Current Applied Physics Vol.2 No.4

In this paper, actuation properties of carbon nanotubes are discussed. Samples of freestanding nanotubes on nanostructured metallic blocks have been prepared. Using a conducting AFM tip, electrons can be injected into the nanotubes. As a consequence,the nanotube expands in a similar way as buckypaper does in an electrolyte. From experimental data, the relative length change isestimated to be less than 1%. These ndings are taken as a demonstration of an electromechanical actuator based on individualsingle walled carbon nanotubes.. 2002 Elsevier Science B.V. All rights reserved.

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>

Electrical Transport Properties of the Alkali Metal Doped Bulk Fullerene ( C60 / C70 )

박억병,심정욱,박혁,박영우,이기범,김하석,Z . Iqbal,R . H . Baughman 한국고분자학회 1991 한국고분자학회 학술대회 연구논문 초록집 Vol.1991 No.10

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>

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>

Do Scores on an Attention Test Predict Scores on Executive Function Tests?

Angela N. Burda,Jaimie L. Gilbert,Courtney Amundson,Kelsey Baughman,Aaron Brummel,(Sarah Crimmins),(Lisa Daringer),(Courtney Hansen),(Delaney Hoffman),(Olivia Ferguson),(Katherine Polit) 한국언어재활사협회 2018 Clinical Archives of Communication Disorders Vol.3 No.3

Purpose: This study sought to determine if younger and older adults’ scores on the Attention Process Test predicted scores on the Behavioral Assessment of Dysexecutive Syndrome and Functional Assessment of Verbal Reasoning and Executive Strategies. Methods: The Attention Process Test, the Behavioral Assessment of Dysexecutive Syndrome, and the Functional Assessment of Verbal Reasoning and Executive Strategies were administered to 60 younger and 60 older adults in a counter-balanced manner. Regression statistics were calculated to determine any predictive outcomes. Results: For older adults, the Attention Process Test significantly predicted the Behavioral Assessment of Dysexecutive Syndrome’s total profile standard scores, and the Functional Assessment of Verbal Reasoning and Executive Strategies’ total standard scores for Accuracy, Rationale, and in one analysis significantly predicted Reasoning. For younger adults, when correcting for high correlations among the five Attention Process Test subtests, this test did not significantly predict their scores on the Behavioral Assessment of Dysexecutive Syndrome or the Functional Assessment of Verbal Reasoning and Executive Strategies’ total standard scores. Conclusions: The Attention Process Test was consistently a significant predictor of executive function measures in older adults, but not younger adults, suggesting the relationship between attention and executive function may be different for these age groups. Thus, different evaluation procedures may be warranted for older adults versus younger adults. A caveat of these findings is that these results were obtained with healthy, neurologically intact individuals. Future research should further investigate the relationship between attention and executive function in adults with acquired neurological damage.

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

Separate and Joint Associations of Shift Work and Sleep Quality with Lipids

Luenda E Charles,Ja K. Gu,Cathy A. Tinney-Zara,Desta Fekedulegn,Claudia C. Ma,Penelope Baughman,Tara A. Hartley,Michael E. Andrew,John M. Violanti,Cecil M. Burchfiel 한국산업안전보건공단 산업안전보건연구원 2016 Safety and health at work Vol.7 No.2

Background: Shift work and/or sleep quality may affect health. We investigated whether shift work and sleep quality, separately and jointly, were associated with abnormal levels of triglycerides, total cholesterol (TC), and low-and high-density lipoprotein cholesterol in 360 police officers (27.5% women). Methods: Triglycerides, TC, and high-density lipoprotein were analyzed on the Abbott Architect; lowdensity lipoprotein was calculated. Shift work was assessed using City of Buffalo payroll work history records. Sleep quality (good, < 5; intermediate, 6e8; poor, > 9) was assessed using the Pittsburgh Sleep Quality Index questionnaire. A shift work þ sleep quality variable was created: day plus good sleep; day plus poor sleep; afternoon/night plus good; and poor sleep quality. Mean values of lipid biomarkers were compared across categories of the exposures using analysis of variance/analysis of covariance. Results: Shift work was not significantly associated with lipids. However, as sleep quality worsened, mean levels of triglycerides and TC gradually increased but only among female officers (age- and raceadjusted p = 0.013 and 0.030, respectively). Age significantly modified the association between sleep quality and TC. Among officers > 40 years old, those reporting poor sleep quality had a significantly higher mean level of TC (202.9 ± 3.7 mg/dL) compared with those reporting good sleep quality (190.6 ± 4.0 mg/dL) (gender- and race-adjusted p = 0.010). Female officers who worked the day shift and also reported good sleep quality had the lowest mean level of TC compared with women in the other three categories (p = 0.014). Conclusion: Sleep quality and its combined influence with shift work may play a role in the alteration of some lipid measures.