Artificial muscle materials

Chemically active plastics such as the polyelectrolytes have been used to make artificial muscle materials. This is an unusual type of mechanical power device that creates motion by the lengthening and shortening of fibers made from a chemically active plastic by changing the composition of the surrounding liquid medium, either directly or by the use of electrolytic chemical action. Obviously this form of mechanical power generation is no competitor to thermal energy sources, but it is potentially valuable in detector equipment that would be sensitive to the changing... 

AIN Artificial muscle materials Electrets Electroactive materials Electromechanically coupled materials Lead zirconate titanate PZT Quartz Zinc oxide... 

Moschou, E.A., S.F. Peteu, L.G. Bachas, M.J. Madou, and S. Daunert. 2004. Artificial muscle material with fast electroactuation under neutral pH conditions. Chem Mater 16 2499. 

The application of muscle to voluntarily control movement and allow locomotion in its various forms is fundamental to animal life and an essential distinguishing feature between animals and plants. One type of animal - humans - seems inherently fascinated by the challenge to emulate nature, and various different types of artificial muscles have been introduced over the past several decades. Some of these different artificial muscle materials can produce muscle-like performances that match, and even exceed in some cases, the performance of natural muscle. As a result of this work, we are getting closer to simultaneously reproducing muscle performance in all of its key attributes force, movement, speed, efficiency, and scalability. 

The global R D effort devoted to artificial muscle materials regularly exposes new actuator materials, and improvements to existing materials. Continuous research will no doubt produce further performance materials and the goal of matching natural skeletal muscle in all its performance attributes is well within reach. 

The presence of polymer, solvent, and ionic components in conducting polymers reminds one of the composition of the materials chosen by nature to produce muscles, neurons, and skin in living creatures. We will describe here some devices ready for commercial applications, such as artificial muscles, smart windows, or smart membranes other industrial products such as polymeric batteries or smart mirrors and processes and devices under development, such as biocompatible nervous system interfaces, smart membranes, and electron-ion transducers, all of them based on the electrochemical behavior of electrodes that are three dimensional at the molecular level. During the discussion we will emphasize the analogies between these electrochemical systems and analogous biological systems. Our aim is to introduce an electrochemistry for conducting polymers, and by extension, for any electrodic process where the structure of the electrode is taken into account. 

Another type of gel expands and contracts as its structure changes in response to electrical signals and is being investigated for use in artificial limbs that would respond and feel like real ones. One material being studied for use in artificial muscle contains a mixture of polymers, silicone oil (a polymer with a (O—Si—O—Si—) — backbone and hydrocarbon side chains), and salts. When exposed to an electric field, the molecules of the soft gel rearrange themselves so that the material contracts and stiffens. If struck, the stiffened material can break but, on softening, the gel is reformed. The transition between gel and solid state is therefore reversible. 

Shahinpoor, M., Elastically-activated artificial muscles made with liquid crystal elastomers. Proceedings of SPIE 7th Annual International Symposium of Smart Structures and Materials, EAPAD Conf, 3987, pp. 187-192, 2000. 

In addition to their potential use as structural composites, these macroscopic assemblies of nanocarbons have shown promise as mechanical sensors [83], artificial muscles [84], capacitors [85], electrical wires [59], battery elements [85], dye-sensitized solar cells [86], transparent conductors [87], etc. What stands out is not only the wide range of properties of these type of materials but also the possibility of engineering them to produce such diverse structures, ranging from transparent films to woven fibers. This versatility derives from their hierarchical structure consisting of multiple nano building blocks that are assembled from bottom to top. 

How Might You Contribute The properties of gel-based materials need to be studied and categorized. In addition, new types of gels with possibly even more startling properties remain to be formulated. The performance of these materials is another area of intense research. For example, the response time of artificial muscle must be very short for the material to function in a natural manner. Natural muscle contracts within 100 ms of receiving the instruction from the brain, which is faster than most responsive gels can perform. 

A minor measure of civilization s progress is that television androids now look more realistic their limbs flex like a human s. Artificial joints and muscles are becoming more realistic as new lightweight soft technologies replace the steels of the industrial age and even the plastics of the twentieth century. Some new materials flex when an electrical impulse is passed through, and others expand more than 100 times when the temperature is raised by 1°C. The nonmetals and metalloids play an important role in these new materials, especially in gels, composite materials, ceramics, polymers, artificial muscle, and luminescent materials. 

Hirai T., Zheng J., Watanabe M., Electrically active polymer materials - application of non-ionic polymer gel and elastomers for artificial muscles in Tao X. (ed.) Smart Fibres, Fabrics and Clothing, Woodhead Publishing, Cambridge. 2001. 

One area where the relationship between the structure of the polymer matrix and the physical processes of the thin layer has been studied in detail is that of electrodes modified with polymer films. The polymer materials investigated in these studies include both conducting and redox polymers. Such investigations have been driven by the many potential applications for these materials. Conducting polymers have been applied in sensors, electrolytic capacitors, batteries, magnetic storage devices, electrostatic loudspeakers and artificial muscles. On the other hand, the development of electrodes coated with redox polymers have been used extensively to develop electrochemical sensors and biosensors. In this discussion,... 

Composite Organic Materials Could Yield Stronger Artificial Muscles, MD DI, Nov. 2002. 

Poly dibenzodiazocine materials have been prepared by polymerization of dibenzoyl-benzidine derivatives using toluene sulfonic acid These agents are useful as electrically conducting artificial muscles. 

The homopolymer showed an enantiotropic nematic mesophase, whereas the diblock copolymer generated microphase-separated lamellae, in which the SCLCP block possessed a nematic-isotropization transition similar to the homopolymer (Table 17). Upon heating, the nematic microphase decreased continuously in the nematic phase from 38.5 nm to 27 nm and showed a constant value of about 26 nm after the nematic-isotropization transition. Therefore, materials in which these block copolymers are macroscopically aligned are expected to show reversible contraction in one dimension, making this polymer system an interesting candidates for an artificial muscle or actuator. 

The objective of Materials Chemistry is to provide an overview of the various types of materials, with a focus on synthetic methodologies and relationships between the structure of a material and its overall properties. Each chapter will feature a section entitled Important Materials Applications that will describe an interesting current/future application related to a particular class of material. Topics for these sections include fuel cells, depleted uranium, solar cells, self-healing plastics, and molecular machines e.g., artificial muscles). 

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