title: Bio-inspired, Moisture-Powered Hybrid Carbon Nanotube Yarn Muscles.
abstract: Hygromorph artificial muscles are attractive as self-powered actuators driven by moisture from the ambient environment. Previously reported hygromorph muscles have been largely limited to bending or torsional motions or as tensile actuators with low work and energy densities. Herein, we developed a hybrid yarn artificial muscle with a unique coiled and wrinkled structure, which can be actuated by either changing relative humidity or contact with water. The muscle provides a large tensile stroke (up to 78%) and a high maximum gravimetric work capacity during contraction (2.17 kJ kg(-1)), which is over 50 times that of the same weight human muscle and 5.5 times higher than for the same weight spider silk, which is the previous record holder for a moisture driven muscle. We demonstrate an automatic ventilation system that is operated by the tensile actuation of the hybrid muscles caused by dew condensing on the hybrid yarn. This self-powered humidity-controlled ventilation system could be adapted to automatically control the desired relative humidity of an enclosed space.
authors.affiliation: Center for Self-powered Actuation and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Shi Hyeong
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Center for Self-powered Actuation and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Cheong Hoon
authors.initials: CH
authors.lastname: Kwon
authors.affiliation: Center for Self-powered Actuation and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Karam
authors.initials: K
authors.lastname: Park
authors.affiliation: Center for Self-powered Actuation and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Tae Jin
authors.initials: TJ
authors.lastname: Mun
authors.affiliation: The Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083, USA.
authors.forename: Xavier
authors.initials: X
authors.lastname: Lepró
authors.affiliation: The Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083, USA.
authors.forename: Ray H
authors.initials: RH
authors.lastname: Baughman
authors.affiliation: Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, New South Wales 2522, Australia.
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Spinks
authors.affiliation: Center for Self-powered Actuation and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea.
authors.forename: Seon Jeong
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D001187:Artificial Organs; D006801:Humans; D006813:Humidity; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D009119:Muscle Contraction; D009132:Muscles / Q000737:chemistry / Q000502:physiology*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D011095:Polyethylenes / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012371:Robotics / Q000295:instrumentation / Q000379:methods*; D047011:Silk / Q000737:chemistry / Q000502:physiology; D013112:Spiders; D013696:Temperature; D013718:Tensile Strength; D014867:Water / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D047011:Silk; D014867:Water; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride