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Eddie C. W. Fok

Bio: Eddie C. W. Fok is an academic researcher from University of British Columbia. The author has contributed to research in topics: Phase (matter) & Diffusion (business). The author has an hindex of 4, co-authored 4 publications receiving 159 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors studied the actuation of yarns of twist-spun multi-wall carbon nanotubes in response to voltage ramps and potentiostatic pulses.
Abstract: We report on actuation in high tensile strength yarns of twist-spun multi-wall carbon nanotubes. Actuation in response to voltage ramps and potentiostatic pulses is studied to quantify the dependence of the actuation strain on the applied voltage. Strains of up to 0.5% are obtained in response to applied potentials of 2.5 V. The dependence of strain on applied voltage and charge is found to be quadratic, in agreement with previous results on the actuation of single-wall carbon nanotubes, with the magnitude of strain also being very similar. The specific capacitance reaches 26 F g−1. The modulus of the yarns was found to be independent of applied load and voltage within experimental uncertainty.

133 citations

Journal ArticleDOI
TL;DR: In this paper, a conducting polymer poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) (PEDOT:PSS) film was inkjet printed onto paper to form a flexible electrochemical double layer capacitor electrode.

23 citations


Cited by
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Journal ArticleDOI
TL;DR: A number of materials have been explored for their use as artificial muscles, but dielectric elastomers appear to provide the best combination of properties for true muscle-like actuation, and widespread adoption of DEs has been hindered by premature breakdown and the requirement for high voltages and bulky support frames.
Abstract: A number of materials have been explored for their use as artificial muscles Among these, dielectric elastomers (DEs) appear to provide the best combination of properties for true muscle-like actuation DEs behave as compliant capacitors, expanding in area and shrinking in thickness when a voltage is applied Materials combining very high energy densities, strains, and efficiencies have been known for some time To date, however, the widespread adoption of DEs has been hindered by premature breakdown and the requirement for high voltages and bulky support frames Recent advances seem poised to remove these restrictions and allow for the production of highly reliable, high-performance transducers for artificial muscle applications

1,299 citations

Journal ArticleDOI
TL;DR: A detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications, including both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.
Abstract: This review comprises a detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications. Soft robots present a special design challenge in that their actuation and sensing mechanisms are often highly integrated with the robot body and overall functionality. When less than a centimeter, they belong to an even more special subcategory of robots or devices, in that they often lack on-board power, sensing, computation, and control. Soft, active materials are particularly well suited for this task, with a wide range of stimulants and a number of impressive examples, demonstrating large deformations, high motion complexities, and varied multifunctionality. Recent research includes both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.

897 citations

Journal ArticleDOI
TL;DR: The various types of natural muscle are incredible material systems that enable the production of large deformations by repetitive molecular motions as mentioned in this paper. But they are difficult to manipulate and require a large amount of energy.

813 citations

PatentDOI
07 Jul 2016
TL;DR: In this article, the authors describe the properties and properties of carbon nanotube yarns, ribbons, and sheets, including extreme toughness, resistance to failure at knots, high electrical and thermal conductivities, high absorption of energy that occurs reversibly, up to 13% strain-to-failure compared with other fibers with similar toughness, retention of strength even when heated in air at 450°C for one hour, and very high radiation and UV resistance, even when irradiated in air.
Abstract: The present invention is directed to nanofiber yarns, ribbons, and sheets; to methods of making said yarns, ribbons, and sheets; and to applications of said yarns, ribbons, and sheets. In some embodiments, the nanotube yarns, ribbons, and sheets comprise carbon nanotubes. Particularly, such carbon nanotube yarns of the present invention provide unique properties and property combinations such as extreme toughness, resistance to failure at knots, high electrical and thermal conductivities, high absorption of energy that occurs reversibly, up to 13% strain-to-failure compared with the few percent strain-to-failure of other fibers with similar toughness, very high resistance to creep, retention of strength even when heated in air at 450°C for one hour, and very high radiation and UV resistance, even when irradiated in air. Furthermore these nanotube yarns can be spun as one micron diameter yarns and plied at will to make two-fold, four-fold, and higher fold yarns. Additional embodiments provide for the spinning of nanofiber sheets having arbitrarily large widths. In still additional embodiments, the present invention is directed to applications and devices that utilize and/or comprise the nanofiber yarns, ribbons, and sheets of the present invention.

661 citations

Journal ArticleDOI
16 Nov 2012-Science
TL;DR: Guest-filled, twist-spun carbon nanotube yarns are designed as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation and can solve the problems of speed and lifetime.
Abstract: Artificial muscles are of practical interest, but few types have been commercially exploited. Typical problems include slow response, low strain and force generation, short cycle life, use of electrolytes, and low energy efficiency. We have designed guest-filled, twist-spun carbon nanotube yarns as electrolyte-free muscles that provide fast, high-force, large-stroke torsional and tensile actuation. More than a million torsional and tensile actuation cycles are demonstrated, wherein a muscle spins a rotor at an average 11,500 revolutions/minute or delivers 3% tensile contraction at 1200 cycles/minute. Electrical, chemical, or photonic excitation of hybrid yarns changes guest dimensions and generates torsional rotation and contraction of the yarn host. Demonstrations include torsional motors, contractile muscles, and sensors that capture the energy of the sensing process to mechanically actuate.

577 citations