Polyacrylonitrile linear actuators: Chemomechanical and electro-chemomechanical properties

Choe, Kiyoung; Kim, Kwang Jin

doi:10.1016/j.sna.2005.09.008

Cited by 36 publications

(35 citation statements)

References 9 publications

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“…Recent work has found that commercial poly(acrylonitrile) (PAN) yarns treated in this way could give actuator strains of about 80 % and stresses of 100 kPa to 1 MPa with a response time of about 10 seconds [114]. The same fibers can be driven electrically at 5 V, using an electrode embedded in or adjacent to the fiber, to produce similar stress but the response time is much longer, about 10 minutes [113,114].…”

Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

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Polymer Gel Actuators: Fundamentals

Calvert

2009

Biomedical Applications of Electroactive Polymer Actuators

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One view of materials development is to search for what materials correspond to empty spaces on a hypothetical multi-dimensional map of the properties of available materials. Following a biomimetic philosophy, for instance, it can be seen that tough ceramics and moldable short fiber composites with high moduli are possible but absent from the list of available synthetic materials. Likewise artificial muscle is missing, where the properties are defined as a developed stress of over 300 kPa, a linear contraction of 25 % and a response time of below one second. Currently dielectric elastomers come closest but have disadvantages [1,2].The actin-myosin muscle system provides the performance target for electroactive polymer actuators [3,4]. The process is driven chemically by the energy change from hydrolysis of the polyphosphate bond as ATP (adenosine triphosphate) binds to myosin and is converted to ADP (adenosine diphosphate) and phosphate. A simple chemical analogy suggests that muscle-like gels should be feasible but it is now clear that the task is much harder than it seems.Early work on gel actuation by Katchalsky-Katzir demonstrated that engines could be built using the chemical energy in diluting a lithium bromide solution to drive contraction and expansion of a collagen belt [5]. In essence, the collagen expands to take up the salt solution or contract to exclude the water. This change is both a molecular conformation change and a volume change. Other chemically driven gels, for instance polyacrylic acid fibers [6] which respond to a pH change, also rely on a solubility change giving rise to a volume change.

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Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

“…The same fibers can be driven electrically at 5 V, using an electrode embedded in or adjacent to the fiber, to produce similar stress but the response time is much longer, about 10 minutes [113,114]. Electrospinning has been used to make fibers of less than one micron diameter that could then be twisted into yarns [115].…”

Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

Polymer Gel Actuators: Fundamentals

Calvert

2009

Biomedical Applications of Electroactive Polymer Actuators

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“…The reversible phenomenon has been applied to the design of chemomechanical mobile systems such as Shahinpoor's swimming robot (Shahinpoor, 1992) or to polymer gel fingers (Hirose et al, 1992). However, the application to linear actuators appears disappointing, as recently reported by Choe and Kin who studied polyacrylonitrile linear actuators (Choe & Kim, 2006): the tested fibre is a 10 mm long 'single strand' consisting of multiple filaments (about 2000) whose diameter in the contracted state is about 0.5 mm, and 1.2 mm in the elongated state; experimentally the fibre can produce a 0.1 N maximum force in both pH activation and electric activation cases, but while this static tension is generated in fewer than 10 s with a 1M HCl acid solution, it takes approximately 10 min for the same result with a 5V electric field.. If the electrostatic approach of ionic polymer-gel based linear actuators is unsatisfactory, it can be asked if more interesting results could be obtained using conductive polymers.…”

Section: B Shape Memory Alloysmentioning

confidence: 99%

Artificial Muscles for Humanoid Robots

Tondu¹

2007

Humanoid Robots, Human-Like Machines

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The question of actuator choice for humanoid robotsIt is important to recall that humanoid robot technology derives from the technology of industrial robots. It is obvious that the developments of bipedal robots such as the integration of robot-upper limbs to complex anthropomorphic structures have benefited from progress in mechanical structures, sensors and actuators used in industrial robot-arms. A direct link is sometimes made between the technology of redundant robot-arms and humanoid robots as underlined in some technical documents of the Japanese AIST where it clearly appears that the HRP2 humanoid robot upper limb is directly derived from the Mitsubshi PA10 7R industrial robot-arm. D u e t o i t s h i g h n u m b e r o f d e g r e e s o f f r e e d o m i n c o m p a r i s o n t o i n d u s t r i a l r o b o t s , ahumanoid robot requires great compactness of all actuator and sensor components. This is why we believe that the harmonic drive technology associated with direct current electric motor technology has played a non-negligible part in humanoid robot development. The DC actuator offers the great advantage of being a straightforward technology, associated with simple and well-known physical models, its integration into mobile robots benefits from new developments in embedded batteries. However, its low maximum-torque-onmass and maximum-torque-on-volume ratios are a serious drawback for its use in direct drive apparatuses. On the other hand, the ability of electric motors to generate very high velocities in comparison with moderate jointed velocities needed by industrial robot-arms and more by jointed anthropomorphic limbs, gives the possibility of using high ratio speed reducers to amplify motor-torque. Moreover, the choice of a high ratio speed reducer offers the advantage of masking inertial perturbations such as external torque perturbations. The technical achievement of such ratios induces specific mechanical difficulties due to the bulkiness of successive gears; harmonic drive technology -represented for example by Harmonic Drive AG -resolves this problem in a very elegant manner: the harmonic drive and the actuator fit together without excessive increase in mass and volume in comparison with the actuator alone. It can be considered that most of today's humanoid robots are actuated by DC motors with harmonic drives (this actuation mode is mentioned, for example, by Honda from its first paper about the P2 robot onwards (Hirai et al., 1998) and then in the official ASIMO web site, as well as in papers concerning other Japanese and European humanoid robots). But if this technology simplifies actuator mechanical integration and leads to the use of simple joint linear control, despite the highly non-linear character of robot dynamics, it is well-known that the use of a speed reducer multiplies the

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“…Previous work has shown that these can be made into muscle-like actuators that respond to pH changes with good force and strain characteristics. 27,28 Recent work has found that commercial PAN yarns treated in this way could give actuator strains of about 80% and stresses of 100 kPa to 1 MPa with a response time of about 10 s. 29 The same fibers can be driven electrically at 5 V, using an electrode embedded in or adjacent to the fiber, to produce similar stress; however, the response time is much longer, about 10 min. 27,29 Electrospinning has been used to make fibers of <1 μm diameter that could then be twisted into yarns.…”

Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

“…27,28 Recent work has found that commercial PAN yarns treated in this way could give actuator strains of about 80% and stresses of 100 kPa to 1 MPa with a response time of about 10 s. 29 The same fibers can be driven electrically at 5 V, using an electrode embedded in or adjacent to the fiber, to produce similar stress; however, the response time is much longer, about 10 min. 27,29 Electrospinning has been used to make fibers of <1 μm diameter that could then be twisted into yarns. Actuator strains of 38% were obtained in cycling from pH 1 to pH 12 with a response time of about 5 s. The research team reported an actuator stress of about 10 kPa, but the data presented for actuation force and swollen fiber diameter suggests this value is actually closer to 1 MPa.…”

Section: Chemically Driven Gel Actuatorsmentioning

confidence: 99%

Gel Sensors and Actuators

Calvert¹

2008

MRS Bull.

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Gels, soft polymeric or composite materials that have a high fraction of water, are often found as structural materials and actuators in nature but have so far not found many uses when fabricated synthetically. We first examine some natural systems such as jellyfish, sea anemones, starfish, legumes, and human tissue, all having interesting ways of moving or otherwise reacting to the surrounding environment. Then we discuss swelling and cross-linking of hydrogels, followed by a look at actuation by electrically, thermally, and chemically stimulated gels, noting that electrical stimulation needs a chemical intermediary to show substantial actuation (comparable to human muscle, for instance). Electroactive gels have great potential as sensors and actuators but their actual uses are mainly restricted to passive drug delivery and matrices for sensors. For most applications as artificial muscles, electrically driven actuators are too weak, but chemically driven actuators look very promising. Better ways of coupling electrical energy to chemically driven gels are needed. AbstractGels, soft polymeric or composite materials that have a high fraction of water, are often found as structural materials and actuators in nature but have so far not found many uses when fabricated synthetically. We first examine some natural systems such as jellyfish, sea anemones, starfish, legumes, and human tissue, all having interesting ways of moving or otherwise reacting to the surrounding environment. Then we discuss swelling and cross-linking of hydrogels, followed by a look at actuation by electrically, thermally, and chemically stimulated gels, noting that electrical stimulation needs a chemical intermediary to show substantial actuation (comparable to human muscle, for instance). Electroactive gels have great potential as sensors and actuators but their actual uses are mainly restricted to passive drug delivery and matrices for sensors. For most applications as artificial muscles, electrically driven actuators are too weak, but chemically driven actuators look very promising. Better ways of coupling electrical energy to chemically driven gels are needed.

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Polyacrylonitrile linear actuators: Chemomechanical and electro-chemomechanical properties

Cited by 36 publications

References 9 publications

Polymer Gel Actuators: Fundamentals

Polymer Gel Actuators: Fundamentals

Artificial Muscles for Humanoid Robots

Gel Sensors and Actuators

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