Motors. Artificial Muscles

In a film, the cooperative effort of the different molecular motors, between consecutive cross-linked points, promotes film swelling and shrinking during oxidation or reduction, respectively, producing a macroscopic change in volume (Fig. 18). In order to translate these electrochemically controlled molecular movements into macroscopic and controlled movements able to produce mechanical work, our laboratory designed, constructed, and in 1992 patented bilayer and multilayer103-114 polymeric 

The flow of an anodic current oxidizes the conducting polymer and the film swells. At the polypyrrole/tape interface, electrochemically stimulated conformational changes in the polymer promote an expansion that 

An electric current can be made to flow in the device twice by using (Fig. 23) a triple-layer design consisting of a conducting polymer, a two-sided tape, and a conducting polymer. When one of the polymer acts as anode, the second acts as a cathode. 

The substitution of the two-sided tape with a film of an ionic conductor gives (Fig. 24) a triple-layered muscle working in air.114 The tape now acts as a solid electrolyte. Nevertheless, the system only works if the relative humidity in air surpasses 60%. Under these conditions, movements and rates similar to those shown by a triple layer working in aqueous solution were obtained. This device was developed in cooperation with Dr. M. A. De Paoli from the Campinnas University (Campinnas, Brazil). At the moment several groups are developing actuators, muscles, and electrochemomechanical devices based on bilayer or multilayer structures.115-125 

Angular Movement Described by the Free End of the Bilayer from the Initial Vertical Position when Submitted to a Potential Sweep from 400 mV to -170 mV at 1 mV s 1 in 0.1 M IJCIO4 Aqueous Solution at Ambient Temperature 

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We are able to construct mechanical arms that reproduce movements quite close to those performed by the human arm. The problem in implanting these arms is that movements have to be coordinated with all the other body movements under the brain s direction. There is one possibility for connecting the electronic systems of the artificial arm to the nervous signals (Fig. 33) coming from the brain in order to obtain coordinated movements separate those signals into different components and amplify every component to drive an artificial muscle or electric motor. 

An actuator converts electrical, chemical, mechanical and other energy into kinetic energy, for example in an electric motor, piezoelectric element, or artificial muscle. Various actuators have been reported using functional polymers to utilize... 

Actuators that generate movements and forces, such as bending, expansion and contraction driven by stimulation of electrical, chemical, thermal and optical energies, are different from rotating machines such as electric motors and internal combustion engines. There are many sorts of soft actuators made of polymers [1-3], gels [4] and nanotubes [5]. Particularly, biomimetic actuators are interesting because of the application to artificial muscles that will be demanded for medical equipment, robotics and replacement of human muscle in the future. 

Even if most of the interest is focused on the development of new materials and on new ways for improving their characteristics as new electrical motors, some stationary state had been attained several years ago, hindering the construction of artificial muscles of any shape and volume, and having any mechanical energy. This apparently classical problem has hindered for more than a decade the development of macroscopic muscles, sensors, and actuators based on CP. 

Valero, L. Arias-Pardilla, J. Cauich-Rodrfguez, J. Smit, M. A. Otero, T. R Characterization of the movement of polyp5UTole-dodecylbenzenesulfonate-perchlorate/tape artificial muscles. Faradaic control of reactive artificial molecular motors and muscles. Electrochim. Acta 2011,10, 3721-3726. 

Comparison of power-to-weight ratios of various engines and motors, natural skeletal muscle and high-strain artificial muscles. 

Future direction of gel robots includes polymer robots assisting human with physical interaction muscle suits wrapping around the elders or athletes to support their movements. Artificial muscles will be used for such systems when strength and durability of artificial muscles improve in the future, although existing personal robots and muscle suits are driven by motors or rubber actuators. This study contributes to design and control artificial muscle suits with small numbers of electric wires which enable dexterous and dynamic motions. 

Natural muscles are controlled by neurons and network of neurons. We can imagine artificial neurons and network of artificial neurons as well. Artificial muscles with motor proteins are studied and attract attention[79]. One direction is to develop deformable machine with real motor proteins, actins and myosins, and neurons. Another direction is to develop neural network software to control distributed artificial muscles. The author has been developing open brain simulator which can emulate the activities of human nervous system for estimating internal state of human through external observation [231]. Such software is also applicable to control artificial muscle systems, which is implemented on the personal robots and humanoid robots in the future. 

To illustrate the need for new approaches to actuation, consider that despite years of effort to develop prostheses (artificial hands and arms) driven by electric motors, currently available systems are still stiff, heavy and noisy. The effort to develop artificial muscles ... 

Anderson lA, Hale T, Gisby T et al (2010) A thin membrane artificial muscle rotary motor. Appl... 

Tliese developments will provide amputees and patients with a variety of motor disorders such as paralysis, amyotropic lateral sclerosis with the means to act and communicate by replacing tlie control of muscles with the control of artificial devices by brain activity. 

Assistive systems that apply FES to restore sensory or motor function are called neural prostheses. A neural prosthesis (NP) could improve sensory or motor function in subjects after cerebro-vascular accident (CVA), spinal cord injury (SCI), and some other diseases of the central nervous system (CNS) [1]. A motor NP applies electrical stimulation to artificially generate muscle contractions required for executing of a functional task in subjects who have lost voluntary control because of a disease or injury. The basic phenomena of the FES are the contraction of a muscle due to the direct stimulation... 

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