Browsing by Author "Haines, Carter S."
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Item Enhancing the Work Capacity of Electrochemical Artificial Muscles by Coiling Plies of Twist-Released Carbon Nanotube Yarns(American Chemical Society) Kim, K. J.; Hyeon, J. S.; Kim, H.; Mun, T. J.; Haines, Carter S.; Li, Na; Baughman, Ray H.; Kim, S. J.; 0000-0001-5845-5137 (Baughman, RH); Haines, Carter S.; Li, Na; Baughman, Ray H.Twisted-yarn-based artificial muscles can potentially be used in diverse applications, such as valves in microfluidic devices, smart textiles, air vehicles, and exoskeletons, because of their high torsional and tensile strokes, high work capacities, and long cycle life. Here, we demonstrate electrochemically powered, hierarchically twisted carbon nanotube yarn artificial muscles that have a contractile work capacity of 3.78 kJ/kg, which is 95 times the work capacity of mammalian skeletal muscles. This record work capacity and a tensile stroke of 15.1% were obtained by maximizing yarn capacitance by optimizing the degree of inserted twist in component yarns that are plied until fully coiled. These electrochemically driven artificial muscles can be operated in reverse as mechanical energy harvesters that need no externally applied bias. In aqueous sodium chloride electrolyte, a peak electrical output power of 0.65 W/kg of energy harvester was generated by 1 Hz sinusoidal elongation. ©2019 American Chemical Society.Item Harvesting Temperature Fluctuations as Electrical Energy Using Torsional and Tensile Polymer Muscles(Royal Soc Chemistry, 2015-09-28) Kim, Shi Hyeong; Lima, M©rcio D.; Kozlov, Mikhail E.; Haines, Carter S.; Spinks, Geoffrey M.; Aziz, Shazed; Choi, Changsoon; Sim, Hyeon Jun; Wang, Xuemin; Lu, Hongbing; Qian, Dong; Madden, John D. W.; Baughman, Ray H.; Kim, Seon Jeong; 0000 0003 5232 4253 (Baughman, RH); Lima, M©rcio D.; Kozlov, Mikhail E.; Wang, Xuemin; Lu, Hongbing; Qian, Dong; Baughman, Ray H.Diverse means have been deployed for harvesting electrical energy from mechanical actuation produced by low-grade waste heat, but cycle rate, energy-per-cycle, device size and weight, or cost have limited applications. We report the electromagnetic harvesting of thermal energy as electrical energy using thermally powered torsional and tensile artificial muscles made from inexpensive polymer fibers used for fishing line and sewing thread. We show that a coiled 27 μm-diameter nylon muscle fiber can be driven by 16.7 ⁰C air temperature fluctuations to spin a magnetic rotor to a peak torsional rotation speed of 70000 rpm for over 300000 heating-cooling cycles without performance degradation. By employing resonant fluctuations in air temperature of 19.6 ⁰C, an average output electrical power of 124 W per kg of muscle was realized. Using tensile actuation of polyethylene-based coiled muscles and alternating flows of hot and cold water, up to 1.4 J of electrical energy was produced per cycle. The corresponding per cycle electric energy and peak power output, per muscle weight, were 77 J kg⁻¹ and 28 W kg⁻¹, respectively.